How to Make It
In a medium bowl, combine the ground chicken with 1/4 cup of the chopped onion, 1 tablespoon of the vegetable oil, 1 teaspoon of the chile powder, 1 teaspoon of salt and the garam masala. Using slightly moistened hands, form the ground-chicken mixture into four 4-inch patties.
In a medium saucepan, heat the remaining 1 tablespoon of vegetable oil. Add the remaining 2 tablespoons of chopped onion and 1 teaspoon of chile powder and cook over moderate heat, stirring, until the onion is softened, about 5 minutes. Add the coconut milk and bring to a boil. Remove from the heat and whisk in the peanut butter and hot water. Stir in the peanuts and season the sauce lightly with salt.
Light a grill or preheat a grill pan. Brush the chicken burgers with vegetable oil and grill over moderately high heat, turning once, until they are golden and crusty and just cooked through, 8 to 10 minutes. Spread the peanut sauce on the rolls. Top with the burgers and lettuce, close and serve.