Place 9 in. (23 cm) cast-iron skillet on grill preheated to medium-high. Add oil. Sauté chicken, shallots, red pepper and chili powder 5 to 8 min., until chicken is browned.
Stir in lime juice, orange juice, fish sauce, honey and Sriracha, if using. Cook 3 to 5 min., until most of the liquid has evaporated. Stir 2 tbsp (30 mL) of the cilantro into the mixture. Remove from heat. Makes about 3 cups (750 mL).
Serve larb mixture in lettuce leaves. Garnish with remaining cilantro and peanuts, if using.
Substitute ground pork or turkey.
Substitute fish sauce with soy sauce.
Alternatively, cook on stovetop in skillet over medium heat.