Slow-fried Onions with Tuna Mayonnaise

Canned tuna with mayonnaise is a popular combination among Japanese kids! It's also a popular ingredient for onigiri (rice ball).

Slow-fried Onions with Tuna Mayonnaise
Photographed by Takeshi Noguchi

Recipe by
Eiko Oba







Calorie count is per serving.

Ingredients (Serves 2)

  • 2 onions (320 g)

    When using sweet onions (onions shipped right after the spring harvest before being dried), reduce the steam-frying time by 1-2 min for each side.

  • [Tuna mayonnaise]

    • 1 can tuna (small can, in oil) (80 g)
    • 3 tbsp mayonnaise
    • 1 tbsp parsley (minced)
    • A pinch of salt
    • A pinch of pepper
  • 2 tbsp olive oil



Cut the onions crosswise in half (see notes). Make a crisscross incision in the root end. Insert toothpicks into the other end to hold the layers in place.


Since the core is tough, make an incision in the root end to speed up the cooking process. Inserting toothpicks in the upper half of the onion will prevent the layers from separating. The core will hold the root end of the onion together, so there's no need to use toothpicks.


Drain the tuna and empty into a bowl. If using chunky tuna, break it up into flakes. Stir in the remaining ingredients.


Heat the olive oil in a frying pan over medium heat. Place the onions, cut side down, and fry for a couple of minutes. Cover and steam-fry for 5-6 minutes at low heat. Turn the onions over and fry for 1-2 minutes at medium heat. Cover, then steam-fry for 5-6 minutes at low heat until soft enough to pierce with a bamboo skewer. Remove the toothpicks, plate up, and serve with the [tuna mayonnaise].


Fry the onions over medium heat until the cut sides are a golden brown. Cover to trap the heat and steam-fry at low heat until thoroughly cooked.


[Confirm the grain of the onion before cutting]
Cutting in half.
Cut the onion in half crosswise, at a right angle to the grain. Cutting across the grain speeds up the cooking process and is recommended when cooking largely-cut onions.