Place cilantro, pepper, garlic powder, and onion salt in the bowl of a blender. Pour in margarita mix, lime juice, orange juice, tequila, triple sec, and honey. Puree on high speed until smooth, then reduce speed to medium-low, and slowly add the olive oil; blend until creamy. Place chicken breasts in a resealable plastic bag or glass bowl; pour marinade overtop and toss to coat. Refrigerate for 5 hours.
Preheat an outdoor grill for medium-high heat and lightly oil grate.
Remove chicken from the marinade, shake off excess, and discard remaining marinade. Grill the chicken until tender and juices run clear, approximately 7 minutes per side.