2 stalks of green onions, white parts chopped fine, tender parts of green stalks rough chopped
Make the marinade by mixing together the soy sauce, sugar, garlic, pepper, sesame seeds, and lemon grass in a medium sized bowl.
Put the sliced sirloin into the bowl and stir well, coating completely all sides of the slices with the marinade. Cover the bowl, and keep in the refrigerator for 3 to 4 hours, even longer if you want.
Turn on your grill, and bring the heat up on high setting.
Remove the sirloin slices from the marinade (you can discard the marinade, although it will still be potent enough for one more use if you want to store it in the fridge) and thread them onto the skewers.
Before putting the loaded skewers on to cook, brush the grill’s grate with oil or spray with a non-stick cooking oil. Grill the meat for about 5 minutes per side, depending on how well you like your beef done.
Either serve the meat still loaded on the skewers, or remove the slices from the skewers and serve on Romaine lettuce leaves.
Garnish your Bo Nuong Xa with the fresh herbs listed above in “Ingredients>For the Garnish”.