In a medium bowl, combine brown sugar, soy sauce, minced garlic, grated ginger, lime juice, and olive oil until well blended. Stir until the brown sugar fully dissolves, then set it aside.

Place chicken breasts or thighs in a dish or resealable bag and pour the marinade over the top. Let marinate for at least 30 minutes at room temperature, or refrigerate for up to 2 hours.

Choose your cooking method: grill, bake at 375°F (190°C), or slow cook.

For grilling, cook the marinated chicken on the grill for 6-8 minutes on each side until fully cooked.

For baking, place the chicken on a lined baking sheet and bake for 25-30 minutes, turning halfway through.

For slow cooking, transfer the chicken with the marinade to the slow cooker. Cook on low for 4-6 hours or high for 2-3 hours.

Adjust flavors of the sauce after cooking by adding lime juice or soy sauce if needed.

Serve the chicken on a platter, drizzle with remaining sauce, and garnish with chopped cilantro.