Cut the beef into 1-inch (2.5cm) wide strips to fit on a skewer.
Whisk the sugar, soy sauce, fish sauce, and water in a bowl until the sugar is dissolved. Add the lemongrass, shallot, garlic, chili pepper, curry powder, and rub into the sauce.
Place the beef and marinade in a plastic zip bag and marinade in the cooler for about 1 hour.
Prepare your grill with a hot and cool zone.
Take the beef out of the bag and scrape off the excess marinade.
Thread the beef strips onto the bamboo skewers.
In a saucepan, add the leftover marinade and bring it to a simmer. Simmer for 5 minutes to sterilize the basting sauce.
Grill the beef on each side for 2 to 3 minutes. Baste with the simmered marinade.