First heat oil in a frying pan cook & onion for 5 mins. Then set aside & cool. Then mix all spices in a small bowl soy sauce, sake, sugar, mirin & 1 tbsp water. Then put ground beef in a bowl add garlic, ginger, onion & mix. Then add beaten egg & knead until it becomes sticky. Then sprinkle salt and pepper & the spice mix.
Next form two hamburger patties. The heat oil in a frying pan & cook beef patties for 6 mins or until cooked. Then set aside & save juices.
Next add mixed spices to the same frying pan & then add katakuriko water mixture & stir until the teriyaki sauce has become sticky. At the same time heat buns in oven or toaster.
Then dredge hamburger patties in teriyaki sauce.
Put the patty on the hamburger bun. Then add the mayonnaise & lettuce.