Prepare oyster mushrooms and tear them into bite-sized pieces.
Slice onion and green onion thinly.
Heat cooking oil in a pan and sauté the onion and green onion.
Add oyster mushrooms and stir-fry.
Season with soy sauce, sugar, minced garlic, and pepper.
Serve the stir-fried ingredients over rice.
Finish by drizzling sesame oil and sprinkling sesame seeds.