In a large bowl, whisk together Roasted Garlic Base Better than Bouillon, brown sugar, olive oil, and apple cider vinegar. Reserve half of the marinade in a small container.
Add chicken thighs to remaining marinade and toss until chicken is coated. Cover and place in the refrigerator for 30 minutes to 4 hours.
When ready to cook, preheat grill to 425 degrees and remove chicken from refrigerator.
Lightly oil the grill grates, then place the chicken thighs on the grill and cook 5 minutes. Flip, then cook the second side 5 minutes more, until internal temperature reaches 165 degrees.
Right before removing chicken from the grill, brush each side with reserved marinade.