Make the marinade in a medium bowl or directly in a marinade bag by combining the olive oil, lemon zest, lemon juice, garlic, oregano, salt, and black pepper.
Add the chicken, cover or zip the bag, and marinate it in the fridge for 20 minutes to 1 hour, up to 4 hours.
Remove from fridge and let the chicken sit out for 5 to 10 minutes so it's not fridge-cold when you cook it. This ensures that the chicken isn't overcooked and cooks to a safe-to-eat temperature without drying out.
Cook it
In a large skillet over medium-high heat, heat up the olive oil. Place the chicken breasts in a skillet and cook for 5-7 minutes on each side, until the chicken is cooked through at an internal temperature of 165F. Butterflied chicken will take half the time.
Remove the chicken from the skillet and let it rest 5 to 10 minutes before slicing and serving.
Notes
This recipe yields enough marinade for 2 lbs of chicken.