01 - In a large mixing bowl, whisk together the 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 each piece to coat thoroughly on all sides. Cover the bowl tightly and refrigerate for at least 2 hours, or up to overnight for deeper flavor penetration.
03 - Preheat the grill to medium-high heat, targeting approximately 400°F. Brush the grill grates generously with olive oil to prevent sticking.
04 - Remove the chicken from the marinade, allowing any excess to 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 juices run clear when pierced.
05 - Transfer the grilled chicken off the heat and let it rest for 5 minutes to allow the juices to redistribute before slicing or serving.