Step 1

Whisk together fish sauce, lime juice, sugar, and chile powder in a medium bowl until sugar is dissolved. Add additional lime juice and sugar to taste. (Jaew should be salty and piquant, with lime and sugar to balance the flavor.) Whisk in sesame seeds, if using.

Step 2

Whisk together oyster sauce, seasoning sauce, sugar, oil, and black pepper in a large bowl. Measure 3 tablespoons marinade into a small bowl; reserve for basting. Add chicken wing flats to remaining marinade in large bowl, and toss to coat. Cover and chill, turning occasionally, 30 minutes.

Step 3

Skewer wings diagonally onto 10 (8-inch) wooden skewers; discard excess marinade. Place skewers on a baking sheet lined with aluminum foil; set aside at room temperature until ready to use.

Step 4

Open bottom vent of a charcoal grill completely. Light charcoal chimney starter filled with briquettes. When briquettes are covered with gray ash, pour onto bottom grate of grill. Adjust vents as needed to maintain an internal temperature of 325°F to 350°F. Place skewers on oiled grates; grill, uncovered, turning occasionally, until chicken is cooked through and lightly charred, 30 to 40 minutes, basting with reserved marinade during last 5 minutes of cooking time. (If using a gas grill, preheat to medium [350°F to 400°F]. Place skewers on oiled grates. Grill, uncovered, turning occasionally, until chicken is cooked through and lightly charred, 30 to 40 minutes, basting with reserved marinade during last 5 minutes of cooking time.) Serve wings hot with jaew.