1. In a bowl or blender/food processor, combine olive oil, minced garlic, lime juice, orange juice (if using), chili powder, smoked paprika, oregano, cumin, salt, and any optional spices or additions. Blend or whisk until well combined. If using cilantro, pulse briefly in the processor to incorporate finely.
2. Place the chicken in a large resealable gallon bag or airtight container. Pour the marinade over the chicken, seal tightly, and gently massage or toss to coat evenly.
3. Refrigerate the chicken for a minimum of 2 hours, ideally 4 hours or up to 24 hours for deeper flavor and tenderness. Avoid exceeding 24 hours to prevent the chicken from becoming dry or stringy.
4. When ready, remove chicken from the marinade and cook by grilling, baking, air frying, or sautéing until the internal temperature reaches 165°F (74°C). For grilling, preheat to medium-high (450-500°F), oil the grates to prevent sticking, and cook about 6-7 minutes per side for thighs or breasts.
5. Let the cooked chicken rest covered for about 5-10 minutes to redistribute juices before serving.