Cut the meat in long thin shreds (0.5 cm maximum width). Peel and cut the garlic cloves in halves.
Put the meat, the garlic cloves, the soy sauce, the fish sauce and the pepper in a bowl and mix thoroughly.
Put the prepared composition in a food container with a sealed lid and place it in the fridge for at least 12 hrs.
Cooking the dish
Preheat a wok pan and put the meat inside without the marinade juice or the garlic cloves.
Cook for 3 mins while tossing the content regularly.
Put the noodles in a heat resistant bowl.
Boil the water and then pour it on the noodles. Leave for 5 mins then drain completely.
Serving
Cut the lettuce in thin shreds and mix with the noodles. Place the cooked beef shreds on top (including the sauce that was created while cooking the meat).