Grilled Huli Huli Chicken

1 c brown sugar packed
3/4 c ketchup
3/4 c low-sodium soy sauce
1/3 c chicken broth
2 1/2 tsp minced fresh ginger
1 1/2 tsp minced garlic
24 boneless skinless chicken thighs (about 5 lbs)  (This makes a TON - I made half a batch)

In a small bowl, mix the first six ingredients.  Reserve 1 1/3 cups for basting; cover and refrigerate.  Divide remaining marinade between two large resealable plastic bags.  Add 12 chicken thighs to each; seal bags and turn to coat.  Refrigerate for 8 hours or overnight.

Drain and discard marinade from chicken.  Moisten a paper towel with cooking oil; using long-handled tongs, lightly coat the grill rack.

Grill chicken, covered, over medium heat for 6-8 minutes on each side or until no longer pink; baste occasionally with reserved marinade during the last 5 minutes.