Mix all the ingredients for burger patties, except for butter, in a large mixing bowl. Take care not to overmix the meat so it won't be tough. Shape them into a patty about 5-inch in diameter and about 1/2-inch thick. You should be able to make about 12 patties
Melt the butter in a large skillet. Cook the beef patties about 3-5 minutes on each side, depending on the doneness you like and also the thickness of the patty. Repeat with the rest of the patty
Dressing the burger:
Brush both sides of the burger with butter and then briefly toast them on the skillet or in a toaster
Place a piece of lettuce, follow by tomato and cucumber if using. Place the meat patty on top. Dress with kewpie mayo and sambal. Top with fried egg and then close with the top bun and serve immediately