Asian Kitchen - Beef slices with colored peppers, on the Chinese way

Beef slices with colored peppers, on the Chinese way

1/2 kilo steak, cut into thin slices2 tablespoons of frying oil3 sliced garlic1 onion, sliced2 colored capsicum (green/red)2 chopped green onionsTo marinate the meat:1 tablespoon of soy sauce1 tablespoon rice vinegar (or white vinegar)1/2 tablespoon bicarbonate of soda3 teaspoons starchSauce:3 tablespoons of oyster sauce2 tablespoons of rice vinegar