Courtesy of Cook's Illustrated. Easy and delicious!
Beef
4 Tbsp vegetable oil
4 Tbsp packed dark brown sugar
2 Tbsp fish sauce
1 (1.5-1.75 lb) hangar or flank steak, cut against the grain into pieces that are approximately 4"x2"x1/4"
Basting Sauce
3/4 cup coconut milk
3 Tbsp packed dark brown sugar
3 Tbsp fish sauce
2 Tbsp vegetable oil
3 shallots, minced
2 stalks lemongrass, trimmed to bottom 6 inches and minced
2 Tbsp grated fresh ginger
1.5 tsp ground coriander