Tokyo: this world-class metropolis is a veritable gourmet wonderland.

Discover the stories behind the ingredients that make this city so delicious - so "oishii."

Today, we focus on a green vegetable called "goya," also known as the bitter gourd.

Goya was apparently brought to Japan's southern Okinawan islands from China in around the 16th century, and it soon became the tropical region's major crop.

Goya wasn't widely available in other parts of Japan until around 1990 - fairly recently.

Efforts to grow the crop outside of Okinawa are well underway.

Novel recipes are popping up everywhere.

Goya - the star of the Okinawan household - is now even used in French cuisine.

With goya, there's truly more than meets the eye.

Trails to Oishii Tokyo.

Hi! It's Kailene.

Today's theme is goya, an ingredient often used in Okinawan cooking.

So, I've come to Okinawa.

I'm excited to learn about goya and discover new and delicious ways of eating it.

Okinawa has a warm climate all year round, averaging around 23 degrees Celsius.

The island is Japan's top producer of goya.

We begin at a farmers' market.

It's the largest one in Okinawa that's run by a farmers cooperative.

They have "shikuwasa."
I often see this as a drink flavor.

I've never seen the actual fruit before.

This is so heavy!

You'll find a number of veggies unique to the tropical region.

Look at that. It's all goya!

They have big ones.

And small ones.

Huge difference.

Are there different varieties?

Yes, many.

The two main types are
abashi goya and standard goya.

- What's the difference?
- Abashi are less bitter, juicier, and meatier.

Standard goya are the ones you often see.

Standard goya found in shops are smaller than the abashi type.

Abashi goya are also thicker, with larger and rounder bumps.

How do you know if they're good?

Straight ones are easier to handle
and tend to be tastier.

The first thing to check is the top,
where it was attached to a vine.

There's a smooth section between
the top and the bumpy part.

It should be shaped a bit like
a mountain, like Mt. Fuji.

When's the best time to buy them?

July and August. Midsummer.

I'm just in time.

Kailene arrives in Naha, Okinawa's capital.

Here, she visits a restaurant serving local cuisine.

Stir-frying it is most common, right?

Yes, it's quite popular.
It's Okinawa's comfort food.

Goya slices and firm tofu are added to a frying pan.

Then a dash of salt.

This is a special Okinawan "dashi" broth made from "katsuobushi," or skipjack tuna flakes, and pork bones.

Stir in some beaten eggs, and it's ready.

"Itadakimasu."

Very tasty.

Goya is bitter, but that's
the nice thing about it.

I agree.

It's good against heat fatigue too.

I don't think we use many bitter
ingredients in American cooking.

It's great to be able to eat things like this in Japan.

Time to up the ante.

This is great too!

Deep-fried goya slices.

Enjoy them with a cold beer.

The goya is on its own, so
I thought it'd be more bitter.

But it's easy to eat, and it goes
great with the lemon.

I slice them and place them in water.

- To reduce bitterness?
- Yes, I chill them.

I let them sit for 5-10 minutes
in iced water before I fry them.

A nice, crispy texture with a light bitterness.

And now...

Here we go.

Deep-fried goya stuffed with minced pork, and simmered in soy sauce.

This is quite different.
This one is sweeter.

Right. It's sweetened.

I've had bitter and meaty dishes
like beef with green peppers.

But this is my first time
eating meat with goya.

Goya plays a leading role in Okinawan cuisine.

The essential veggie also protects the body against heat exhaustion.

Goya has been cultivated in Okinawa since it arrived in the region in the 16th century.

An old medical document about regional plants and herbs details its health benefits.

Bittersweet goya regulates body
temperature, reduces heat and
fatigue, and improves vision.
Eat it every day in summer.

A local research center is working hard to improve agriculture through breeding experiments.

New varieties include cold-resistant ones and others that can be grown in large numbers.

We consider goya to be an
Okinawan vegetable.

Why is that?

One reason is they've been grown and
eaten here for a very long time.

Also, Okinawan produce couldn't be
exported while under US administration.

Okinawan produce couldn't be exported until 1972, when the island was reverted to Japanese control.

So, it wasn't eaten on the
main island until recently?

Exports increased after Okinawa
grew popular several decades ago.

After that, it was more widely
available on the main island.

Another reason is that Okinawa had
a problem with melon flies in the past.

- A type of fruit fly?
- Right.

Melon flies lay eggs on vegetables, causing them to rot.

The pest was a major concern in many parts of the world.

An infestation in Okinawa forced the Japanese government to impose strict regulations on the island's produce.

The infestation was finally eradicated in 1993, allowing goya to be shipped across Japan.

Gima shows Kailene a new goya variety that's currently under development.

- Right here.
- Wow. Nicely lined up.

This is our new goya, Kenko 7.

What's unique about it?

It's similar to abashi goya.

Instead of changing the flavor and shape,
we increased the number of flowers.

That improved the yield.

All of the flowers will grow goya?

Goya have both male and female flowers.

- This is a female.
- I see.

- There's a baby goya under the petals.
- How cute!

We give them pollen from the
male flowers to help them grow.

Let's see how pollination works.

This orange part is the pollen.

I rub it on the same part of the
other flower that isn't orange?

Yes, the green part.

A petal fell off. Is that okay?

Morning is the best time
for cross-pollination.

After that, petals will fall off.

Time for a taste test.

Standard goya is up first.

Now for the new type.

My first time eating raw goya.

I wondered what it would taste like.

It has a nice bitter flavor and good texture.

The new type seems to have
more moisture, and it's less bitter.

It'd be great in a salad.

Goya, the Okinawan treasure now available across Japan, continues to evolve.

My first trip to Okinawa!

Generations of careful cultivation turned goya into a local star.

Tatebayashi, Gunma, is in the northern part of the Kanto region.

In summer, the city has reached over 40 degrees Celsius.

Seeing an opportunity there, local farms began growing goya.

The area is now a leading producer.

Wow. So much goya.

Look at these.

Hello. Nice to meet you.

Meet Uchida Kunio, head of the local farmers cooperative.

Does it have to be hot to grow goya?

It does.

The climate is just right here?

Gunma has the right climate.

It's been too hot recently, though.

They used to grow spinach, but it couldn't stand the heat, so they started growing goya about 20 years ago.

What's special about Gunma goya?

We grow a variety that's less
bitter than Okinawan goya.

Why is that variety grown here?

People in this region
weren't familiar with goya.

They kept saying they couldn't
eat it because it was too bitter.

Vines grow on raised nets with plenty of room to spare.

Is this so the leaves get enough sunlight?

Both the leaves and the goya
need lots of sunlight.

- The goya too?
- Right. Otherwise, the goya won't turn green.

If the leaves are overcrowded,
the skin will turn white.

Interesting.

During peak season, how many
do you pick in one day?

In one day? 3,000.

That many?

- All by hand?
- Yes.

- Every day?
- Right.

Wow!

Utilizing the hot climate in this way has given birth to a new regional star.

Kailene will meet some special players in the fight to enhance goya's popularity.

This high school was founded in 1912.

In addition to the standard curriculum, it offers bioproduction, green science, and food science classes.

- Hi!
- Hello.

Now seniors, this group has been researching goya during all three years of high school.

Their activities include hands-on goya cultivation and visiting factories to explore ways of incorporating the food into school lunches.

I hear you're working hard with goya.

We hold green curtain and recipe contests
to promote local goya consumption.

I didn't expect high school students
to be doing such things.

The goya green curtain and recipe contests received entries from all across the country, and spanning all age groups.

What's a green curtain contest?

You set up a net and grow goya on it,
letting the vines create a green curtain.

In the contest, curtains are judged by their size.

- You choose the best goya curtain?
- Exactly.

How cute. And fun!

More and more green curtains are covering windows and buildings around Japan to battle the scorching heat.

They're made using the vines of goya, sponge gourd, or morning glories.

Effective in blocking direct sunlight, they can reduce energy output by up to 80%.

For the recipe contest, we get entries
from all over the country.

Really? Not just Gunma?

Places like Tokyo and Shizuoka too.

- Any interesting recipes?
- Yeah.

- Like what?
- Like...

- Goya mixed with vanilla ice cream.
- Was it good?

Well...

What recipes have won?

Goya steamed rice.

- Goya rice balls.
- That sounds good.

And goya dry curry.

Dry curry. I bet that's good!

It was tasty.

Do you make your own recipes too?

We do.

They made bread using dough mixed with goya that was dried and powdered.

It was a hit, even among students who don't like goya!

Now, Kailene will learn a prize-winning recipe.

Here are the ingredients.

- About this thick?
- That's good.

Rub them with salt and sugar.

Rub it?

Here we go.

Let it sit for about ten minutes to release moisture.

Now we boil them.

In water?

But we just let out the moisture.

Why do you boil them
after soaking up moisture?

When you add salt,
the bitterness comes out.

Pour in some seasoned dashi, called "shiro dashi."

Pickled ginger and cream cheese go in next.

- That'll do.
- Lovely colors.

I haven't made rice balls in a while.
I hope I still know how.

These days I just buy them.

You're good at shaping them.

- I used to make them in the US too.
- Really?

When I was longing for Japanese food.

- It's ready now.
- So cute!

It looks so good
I can't wait to eat it.

- Go ahead.
- "Itadakimasu!"

- Do you like it?
- "Oishii."

Is it good with goya?

It really is!
Cream cheese with goya.

The sourness and spice of the pickled ginger
kicks in, but it doesn't overpower the goya.

It's a nice balance of flavors.

- People who don't like goya could eat this.
- Nice.

Support extends from the local farms to high schools!

I could really feel Gunma's commitment to goya.

Back in Tokyo, Kailene heads to a French restaurant in Daikanyama, an area with many high-end restaurants.

Meet owner chef Ishigaki Hitoshi.

Originally from Iriomote, Okinawa's second-largest island, he prides himself in using ingredients from his home turf.

What will he serve first?

A drink?

With goya?

A muscat grape and goya cocktail.

Interesting. I've never had a goya drink.

I cook the goya to reduce its
grassy flavor, and add cold muscats.

I can't wait to try it.

- It's excellent.
- Thank you.

I always expect goya to be bitter.

This was sweet at first.

The bitterness of the goya
came out in the aftertaste.

Interesting and tasty.

Things like green tea and
coffee can be bitter too.

But pairing bitter with fruity
isn't that common, so I was skeptical.

But it's very good!

I made a broth from tomatoes and
kombu kelp, and jellied it.

The goya on top is lightly salted.

- This is great too!
- Thank you.

Goya alone is quite bitter.

But it's pretty mild with the jelly.

- It balances it out.
- Right.

The jelly has a soft texture, of course.

I never realized how crunchy goya is
until I ate it raw for the first time.

Preparing goya with salt
takes away its bitterness.

But too much will ruin the texture.
It's difficult to get it right.

Now, he appears to be making that famous Okinawan dish we saw earlier...

What do we have here?

- Goya "champuru."
- Wait, what?

Goya champuru?

A goya champuru...

Quiche.

Topped with parmesan cheese and katsuobushi.

It has canned pork in it, so the ingredients
are basically the same as goya champuru.

I added sour cream to make it rich.

That explains a lot. It has a thick texture
you don't often have in Japanese food.

It's goya champuru with a unique twist.

- Delicious.
- Thank you.

You served three goya dishes today.
Is goya a key ingredient for you?

Yes. The concept of this restaurant is French
cuisine made with Okinawan ingredients.

Goya is the most famous Okinawan food,
so we've served this quiche from day one.

- Is it popular?
- Yes. I'd say it's our top seller.

Goya - the pleasantly bitter veggie I hadn't eaten much before coming to Japan.

On my first trip to Okinawa, I learned that goya is deeply rooted in the region's culture and history.

And I experienced first-hand how the whole country has fallen in love with goya.

It's the vegetable of choice for battling the Japanese summer heat.

In Tokyo, every ingredient has its own story.