Heat oil in a large frying pan; saute onion and garlic until transparent.
Add cabbage or sprouts, increase heat, and stir constantly for 3 or 4 minutes.
Add soy sauce, salt, and pepper to taste.
Continue to cook and stir constantly another 3 to 4 minutes.
Combine water and cornstarch until smooth.
Pour into cabbage mixture and stir until cornstarch mixture is clear.