1. Slice onion into ring-shape and cover it with water to remove acrid smell.
Slice tomato into 1cm and toast hamburger buns per side slightly.
2. Heat oil in pan with hamburger steak over medium heat.
When steak is almost done, serve sauce over steak then toast hamburger buns per side.
3. Spread mayonnaise on one side of hamberger bun. Place lettuce, onion, tomato, hamberger steak, hamburger bun in the order named.