01 - In a large mixing bowl, whisk together mayonnaise, lemon juice, minced garlic, Dijon mustard, smoked paprika, dried oregano, salt, and black pepper until smooth and well combined.
02 - Add the chicken breasts to the marinade, turning to coat each piece thoroughly. Cover the bowl with plastic wrap and refrigerate for at least 2 hours, or overnight for deeper flavor penetration.
03 - Preheat the grill to medium-high heat, targeting approximately 400°F. Brush the grill grates with olive oil to prevent sticking.
04 - Remove the chicken from the marinade, allowing any excess to drip off. Place the breasts on the hot grill and cook for 6 to 8 minutes per side, until the internal temperature registers 165°F and juices run clear.
05 - Transfer the grilled chicken to a cutting board and let it rest for 5 minutes before slicing or serving to allow the juices to redistribute.