In a medium bowl whisk together the dijon mustard, olive oil, honey, grated garlic, onion powder, salt, and pepper. If you want to thin out the marinade then add 1 tablespoon of water at a time or until you get the desired consistency. Reserve 1/4 cup of the marinade to brush over the chicken after it cooks.
Place chicken into a ziploc bag with the marinade.
Place it the refrigerator and marinade for 1 hour or longer. If you can marinade this overnight that'd produce the best favor.
Discard the marinade and cook chicken on a clean hot grill over medium high heat. Cook 5-7 minutes on each side or until the internal temperature is 165 degrees.
Remove from grill and brush remaining marinade over the cooked chicken.
Serve with your favorite side.