01 - In a large mixing bowl, whisk together the mayonnaise, lemon juice, minced garlic, Dijon mustard, smoked paprika, dried oregano, salt, and pepper until the mixture is smooth and well combined.
02 - Add the chicken breasts to the bowl, turning each piece to coat evenly in the marinade. Cover tightly and refrigerate for at least 2 hours, or up to overnight for the most flavorful results.
03 - Preheat the grill to medium-high heat (approximately 400°F). Brush the grill grates with olive oil to prevent sticking.
04 - Remove the chicken from the marinade, letting any excess drip off. Place the breasts onto the hot grill and cook for 6 to 8 minutes per side, until the internal temperature registers 165°F and the juices run clear.
05 - Transfer the chicken off the grill and let it rest for 5 minutes before slicing or serving to allow the juices to redistribute.