Combine the lime juice, orange juice, olive oil, tequila, garlic, cilantro, cumin, sugar, optional chili powder, salt and pepper in a large bowl or zip closure bag then stir or shake until all ingredients are mixed well.
Butterfly the chicken breast, seasoning it will salt, pepper and dried basil. Once seasoned, add chicken breast to the marinade.
Marinate for at least 20 minutes in the refrigerator, or overnight for best, most flavourful results.
Heat grill or pan to medium-high heat. Remove chicken from the marinade and cook for 5–7 minutes per side, turning once (or until cooked through).
Once cooked, remove chicken from grill or pan, letting it rest for 5-10 minutes before serving. Plating can be completed during this time.
Once plated, you can add the orange and/ or lime zest (to taste) to the top of the chicken to bring more colour and flavour to your dish.