In a medium bowl, whisk together brown sugar, soy sauce, minced garlic, grated fresh ginger, lime juice, and olive oil. Place your chicken breasts or thighs into a resealable bag and pour the marinade over the chicken, ensuring it's well coated. Seal the bag and let it marinate in the refrigerator for at least 30 minutes, or ideally up to 2 hours.

Depending on the cooking method chosen, preheat your grill to medium-high heat, your oven to 375°F (190°C), or prepare your slow cooker by setting it to low.

For the grilling method, remove the marinated chicken from the bag and let excess marinade drip off. Place the chicken on the preheated grill and cook for about 6-7 minutes per side, or until the internal temperature reaches 165°F (75°C).

For baking, arrange the marinated chicken in a greased baking dish and bake in the preheated oven for approximately 25-30 minutes, ensuring it reaches an internal temperature of 165°F (75°C).

For slow cooking, place the marinated chicken directly into the slow cooker and cook on low for 4-6 hours or on high for 2-3 hours.

Once cooked, taste the sauce. If too sweet, add additional lime juice or soy sauce for balance. Serve hot, garnished with fresh cilantro.