Combine 2 tablespoons soy sauce, sesame oil, ginger, garlic, sugar and pepper to create a marinade. Add the chicken and refrigerate at least 1 hour.
Cover and soak long rice in cold water for 30 minutes. Cut into eight lengths. (Smaller lengths can be used based on preference.)
Place a large skillet or wok over high heat. When hot add vegetable oil and marinated chicken. Cook until chicken no longer is pink, turning often. Reduce heat and add mushrooms, green onions, long rice, chicken broth and remainder of soy sauce. Simmer until hot, stirring often - about 3 minutes.
Note - Long rice requires very little cooking time. It absorbs liquid very easily and can easily break down if cooked too long.