Saw this the other day in an article, and did a mental tick box of ingredients involved so no shopping required. A tuna katsu sandwich. Apart from the tuna steaks, there's a slaw of cabbage and pickled ginger, and a tonkatsu sauce.
Made the tonkatsu sauce first of all, a mix of tomato ketchup, mirin, soy and Worcestershire sauces, some grated garlic and a pinch of chilli flakes.
The tuna steaks are going to be breadcrumbed and fried. Here's the prep, along with the slaw and a small apple and toasted sesame seed salad.
Tuna ready.
Only a minute or so each side.
Tonkatsu sauce spread on both sides of the bread, with slaw on one side.
Tuna steak goes on top of the slaw.
Decent lunch.