Clean and cut lettuce into bite size pieces. Keep refrigerated until ready to use.
Separate noodles into strands and stir-fry in heated non-stick wok or skillet. Add 4 tbsp black soy sauce, and stir until noodles become brown and a little crispy on the bottom. Remove to a bowl, and set aside.
Heat oil in the same wok, and sauté garlic until aromatic. Add ground beef and stir to break up meat and brown it. Add curry powder and ground pepper. Mix well until beef is done. Add chopped onion and tomatoes. Stir well and saute about 5 minutes with the beef mixture.
Add chicken broth to beef mixture and add seasoning ingredients. Taste and adjust for proper balance of sweet/sour/salty.
Mix cornstarch and water, and make a slurry. In a slow stream, add slurry to broth in pan, stirring constantly to keep it from getting lumpy. Boil until the sauce is thickened. Lower heat and simmer a few minutes.
To serve, place lettuce on plates. Put noodles on the lettuce. Put a scoop of beef sauce on top of the noodles, sprinkle with ground pepper and a little bit of Sambal oelek.