Caramelize the onions by sautéing it in some oil.
Spread it out on a plate and allow to cool for 5-10 mins.
Mix all the ingredients together except the oil.
Do not over-mix it or the patty will be tough.
Divide mixture into 4, and shape into patties.
Chill if needed or if you have time.
Heat the same pan on med high, add oil.
Pan fry on both sides until cooked.