Unbelievable Chicken

I'll post the original recipe, but I made this in the crock pot with 2 lbs of chicken thighs. I just mixed the "marinade" and poured it over the frozen chicken and cooked it on low in a 3 qt crock. I would think 6-8 hours on low...I was running out of time and put it on high after about 5 hours. It is good, I'm not sure "unbelieveable" but good nonetheless.

Unbelievable Chicken
1/4 cup cider vinegar
3 tablespoons prepared coarse-ground mustard
3 cloves garlic, peeled and minced
1 lime, juiced
1/2 lemon, juiced
1/2 cup brown sugar
1 1/2 teaspoons salt
ground black pepper to taste
6 tablespoons olive oil
6 skinless, boneless chicken breast halves

In a large glass bowl, mix the cider vinegar, mustard, garlic, lime juice, lemon juice, brown sugar, salt, and pepper. Whisk in the 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 to 8 minutes per side, until juices run clear. Discard marinade.