Place the onion slices in hot water with salt and 2 tablespoons of vinegar for 10 minutes. Drain, set aside.
Roll one cheese slice per ham slice forming "tacos". Place oil on a skillet and heat the tacos slightly, until the cheese melts. Place in plates and cover with mole sauce (previously heated).
Spread some sesame seeds and onion slices over the tacos. You can garnish with rice and avocado.