In a pot over low heat, add olive oil, onion and slowly stir-fry for 45 mins until the onions get caramelized. Keep adding drops of water every time the onion gets too dry.
Add water, Sempio Soy Sauce and boil for 5 mins.
Toast the bread under the broiler. Place grated cheese over the bread slices and place them back under the broiler to melt the cheese.