Prepare the Chicken:

1. If your chicken breasts are particularly thick, you can lightly pound them to an even thickness (about 3/4 inch or 2cm) for more uniform cooking. Alternatively, you can slice thicker breasts in half horizontally to create thinner cutlets. Pat the chicken dry with paper towels.
2. Combine Marinade Ingredients: In a medium-sized non-reactive bowl (glass or ceramic is ideal), whisk together the extra virgin olive oil, fresh lemon juice, red wine vinegar, and Dijon mustard until lightly emulsified.
3. Add Aromatics: Stir in the minced garlic, dried oregano, chopped fresh rosemary, sea salt, black pepper, and the optional pinch of red pepper flakes. Mix thoroughly to ensure all seasonings are well distributed.
4. Marinate the Chicken: Add the chicken breasts to the bowl with the marinade. Turn each piece to ensure it’s fully coated. Cover the bowl tightly with plastic wrap or transfer the chicken and marinade to a resealable plastic bag, pressing out any excess air. Refrigerate for at least 1.5 hours, or up to 3 hours for deeper flavor. Do not exceed 4 hours, as the acidity can start to negatively affect the chicken’s texture.

Cook the Chicken:

1. Grilling (Recommended): Preheat your grill to medium-high heat (around 375-450°F or 190-230°C). Lightly oil the grates. Remove chicken from the marinade; let excess drip. Discard the marinade—do not reuse. Use clean tongs and a clean plate for cooked chicken. Grill for approximately 5-8 minutes per side, depending on thickness. Chicken is done at 165°F (74°C) in the thickest part and juices run clear—no pink remains.
2. Pan-Searing: Heat 1 tbsp olive oil in a large skillet over medium-high heat (do not add more). Once the oil is shimmering, add the chicken. Cook 5–8 minutes per side until golden; internal temp 165°F (74°C) and juices run clear—no pink remains. Avoid overcrowding the pan; cook in batches if necessary.
3. Rest and Serve: Once cooked, transfer the chicken to a clean cutting board. Let it rest for 5-7 minutes before slicing or serving whole. This allows the juices to redistribute, ensuring a more tender and flavorful result. Serve warm.