Boil an egg, chop the white finely, mash the yolk with a fork, and mix with salt, pepper, and mayonnaise.

Mix tuna with mayonnaise.

Season chicken thigh with salt and pepper, heat salad oil in a pan, and cook the chicken skin-side down.

Flip the chicken, cover the pan, and steam for 8 minutes on low heat.

Add the sauce mixture (sugar, soy sauce, mirin, vinegar) to the pan, coat the chicken, and simmer until thickened.

Cut the crusts off the bread and prepare lettuce to match the bread size.

For egg sandwich: Spread lettuce and half of the egg mixture on bread, roll tightly, wrap in plastic, and let it set before cutting.

For ham sandwich: Layer lettuce, cheese, and ham on bread, roll tightly, wrap in plastic, and let it set before cutting.

For tuna sandwich: Spread lettuce and half of the tuna mixture on bread, roll tightly, wrap in plastic, and let it set before cutting.

For teriyaki chicken sandwich: Spread mustard and mayonnaise on bread, add lettuce and sliced teriyaki chicken, roll tightly, wrap in plastic, and let it set before cutting.