Otoro steak with sauteed onions

Make a cut in the back of the fatty tuna, place it in a bowl with Happomibijin, and rub it in to season it

Slice the onion perpendicular to the grain and fry in a frying pan with salad oil. Fry slowly over low heat to evaporate the moisture and avoid burning. Add butter and salt, and once everything is mixed, remove from heat

Heat another frying pan over high heat and fry the fatty tuna fillets (1). They will cook quickly, so quickly flip them over to cook both sides, then remove to a serving dish

[3] Add Happomibijin and sugar to the frying pan and heat to make the sauce

Add the sautéed onions from [2] and pour the sauce from [4] over it. Finish by topping with wasabi to taste