2 tablespoons vegetable oil
1 ciabatta or baguette, or your preferred bread, toasted
2 large onions, peeled and sliced
2 tablespoons butter, softened
2 (8-ounces total) very thin minute steaks
2 tablespoons yellow mustard
Salt and freshly ground black pepper
Place a skillet on the stove and add half the oil along with the onions. Pan-fry on high heat until golden brown and a bit crispy around the edges, 10 minutes.
Move the cooked onions over to the edge of the pan and increase the heat. Add another tablespoon of oil. Season the steaks on both sides with salt and pepper and put them in the pan. Cook for 45 seconds on each side. Turn off the heat.
Cut bread in half and toast on both sides either on a grill pan or under the broiler. Spread with butter and loads of mustard. Pile on the onions and slice the steak before loading onto the sandwich.
Put on the top half of toasted bread and dunk into more mustard while you eat.