Step 1

In a bowl large enough to hold the chicken, whisk the mustard and mustard powder, vinegar, sugar, hot sauce, Worcestershire sauce, garlic, onion, butter, salt, and pepper to taste.

Step 2

Season the chicken well with salt and pepper. Add to BBQ sauce. Toss until coated well. Let sit at room temperature for 1 hour.

Step 3

Preheat an outdoor gas grill or charcoal grill to medium heat. Brush the grill grates generously with oil. Grill the chicken, covered, basting occasionally with the sauce, about 10 to 15 minutes per side.