Combine the mustard, garlic, thyme
and horseradish (if using) in a bowl or container large enough to accommodate the
chicken breasts. Coat the chicken breasts with the mixture and let stand at least
Grill (or broil) about 5 minutes
per side, or until chicken is cooked through (internal temperature of 165°F).
To switch things up, try
substituting fresh oregano for the thyme. Or, if you like a bit of crust, roll in
unseasoned, gluten-free bread crumbs before grilling. Or sprinkle with toasted sesame