Unbelievable Chicken from here
1/4 cup cider vinegar
3 Tbsp prepared coarse-ground mustard
3 cloves garlic, minced
1 lime, juiced
1/2 lemon, juiced
1/2 cup brown sugar
1 1/2 tsp salt
ground black pepper to taste
6 Tbsp olive oil
6 skinless, boneless chicken breast halves
In a large glass bowl, mix all ingredients except olive oil and chicken. Whisk in olive oil. Place chicken in the mixture. Cover and marinate 8 hours or overnight.
Preheat an outdoor grill for high heat.
Lightly oil the grill grate. Place chicken on the prepared grill, and cook 6-8 minutes per side until juices run clear. Discard marinade.