Wash the beef chuck by sprinkling a generous amount of salt on it. Gently rub the salt into the meat and rinse the salt off using warm water. Pat the beef chuck dry using paper towels.
Thinly slice the beef chuck and set it aside.
Chop the garlic and shallots and set aside.
Peel the edible luffa first, then rinse it with water.
Cut the edible luffa into halves first, then slice each half into ½ inch diagonals and set it aside.
Combine in a bowl, thinly sliced beef chuck, ½ chopped garlic, ½ chopped shallots, ½ salt and ½ pepper. Mix well and let it marinade for 15 minutes.
Add vegetable oil into a pan and let it heat up. Then add the marinated beef into the pan along with the fish sauce and sauté until meat is cooked.
Remove the cooked beef from the pan and set aside.
Place the remaining vegetable oil, chopped garlic and shallot into the same pan and let sauté for 2 minutes.
Add the edible luffa, remaining salt and pepper and sauté until it's cooked (a.k.a. until it's translucent).
Add the cooked marinated beef back into the pan with the edible luffa.
Then add in the chicken powder and stir to combine.
Add in the soaked vermicelli (optional) and let the mixture cook on low for another 5 minutes before serving over rice or alone.