Soak lap cheong sausage in a pan of hot water for about 10 minutes. Casings should puff up. Remove casings and slice at a diagonal.
Wash and drain brussel sprouts. Cut off the tops and remove any bruised outer dark green leaves. Then slice each sprout thinly.
Heat a wok or large pan. Fry lap cheong until lightly brown, about 2 minutes. There is no need to use any oil. Remove, leaving the oil in the wok. Set aside.
Add vegetable oil. Sauté garlic for about 30 seconds.
Add brussel sprouts, pepper, and soy sauce. Stir fry for about 4 to 5 minutes.
Return lap cheong to the pan. Stir to get all ingredients well mixed. Turn off heat.
Remove and serve immediately.