150g beef sirloin, thinly sliced
2 tablespoons soy sauce
1 tablespoon vegetable oil
1 garlic clove, minced
1/2 onion, sliced
1/2 red bell pepper, sliced
1/2 green bell pepper, sliced
1/2 carrot, julienned
1 tablespoon cornstarch
1 tablespoon water
Cooked rice or noodles, for serving