Soak the wooden skewers in water for at least 2 hours before grilling. Doing so will prevent the skewers' ends from burning on the grill.
Wash and soak the sweet chilli peppers in room-temperature water for 15 minutes.
Wash the meat, the cut into 1-inch cubes and set aside in a large bowl.
Tenderize the lemongrass stalks with the flat side of the butcher knife on top of a cutting board.
Slice the softened lemongrass into thin rings using the butcher knife and put in the mortar.
Cut galangal into thin slices and place into the mortar.
Clean the garlic cloves and place them into the mortar.
Shred lime tree leaves into narrow strips with a knife and place the strips into the mortar.
Remove the turmeric skin with a knife and place the turmeric into the mortar.
Crush the lemongrass, lime tree leaf, garlic, galangal, and turmeric inside the mortar until you're left with a homogenous paste.
Mince the soaked sweet chilli peppers into a paste using the butcher knife.
Add the paste from the mortar, and the chilli pepper paste into the bowl with the beef.
Add MSG, sugar, and salt (or fish sauce) to the mix.
Mix the beef and all the other ingredients evenly in the bowl, and marinade ingredients for at least 30 minutes (the longer the better!)
Thread the beef onto the skewers.
Preheat the grill to 300F and put the skewers in and cook for 15 minutes, or until an internal temperature of 145F. Rotate the skewers with tongues every 2 minutes.
Serve the beef skewers with vegetables of your choice -- we'd recommend this green papaya salad!