Wash the mustard greens. Separate the chopped stems from the chopped leaves.
Put oil in the pan or wok on medium-high to high heat.
Add the garlic at the same time and stir gently in the oil
Add chopped Thai chili pepper, if using
Stir in the chicken, being sure to break apart any big chunks.
Add the salt
Toss in the mustard green stems, seasoning sauce, and oyster sauce, and then gently stir.
Cover the pan and let it cook without stirring for one minute.
Give it another gentle stir and cover for another 1-2 minutes, and then uncover. If you over-stir, the greens will darken.
Stir in the mustard green leaves and give the dish a gentle stir, and fold.
Let cook for about a minute, and then give the dish another gentle stir and fold. Be sure not to cover the dish again while it’s still cooking.
To avoid overcooking, remove the pan from the hot stove and don’t cover the dish again until it has cooled down.
Prepare the rice on a plate. Scoop the stir-fry on top