Egg & Beef Bulgogi Burger Recipe, Homemade Korean BBQ burger

* Ingredients: cooking oil, 1/2 cup chopped onion, 100ml water, 4Ts soy sauce, 2Ts sugar, 2Ts rice wine, 2Ts oyster sauce, 2Ts ketchup, 1Ts minced garlic, 2Ts de water, 1Ts corn starch, 200g ground beef, 1 yolk, pepper, sal, a pinch of nutmeg, 2Ts All purpose flour, 1 egg, lettuce, hamburger bun