In a large bowl, whisk together the brown sugar, soy sauce, minced garlic, grated ginger, lime juice, and olive oil until well combined. Add the boneless skinless chicken breasts or thighs, ensuring they are fully coated in the marinade. Cover the bowl and refrigerate for at least 30 minutes, preferably 2 hours.

Preheat your grill to medium-high heat or the oven to 400°F (200°C). For slow cooking, prepare your slow cooker on low.

Before cooking, taste the marinade and adjust as needed. Mix in more lime juice for tanginess or extra soy sauce for depth. Sprinkle in chili flakes for spice if desired.

For grilling, cook the marinated chicken for about 6-8 minutes on each side, until the internal temperature reaches 165°F (75°C). If baking, place in a baking dish and cook for 25-30 minutes, turning halfway. For slow cooking, place chicken in the slow cooker with all the marinade and cook for 4-6 hours on low.

Remove the chicken from the heat and let it rest for 5 minutes. Drizzle pan juices over the top and garnish with cilantro. Serve with jasmine rice or a fresh salad.