1/4 c. Dijon mustard
1/4 c. whole-seed (old-style) mustard
1/4 c. hot German mustard
1/4 c. distilled white vinegar
1/4 c. olive oil
1/2 c. apple juice
Juice of 1/2 lemon
Fresh ground pepper

Combine all ingredients. Whisk to emulsify. Marinate chicken 1-3 hours before grilling.