In a bowl, mix the vinegar, lemon juice, mustard, minced garlic, olive oil, salt, and pepper.

Add your wet mixture and your chicken breasts to a container or ziplock bag. Refrigerate, turning massaging the chicken breasts occasionally, for at least 2 hours. This can marinate for up to one full day.

Preheat the oven to 400 degrees F. Put your chicken breasts into a backing dish and drizzle over with the leftover marinade. Cook for 35-40 minutes, basting with the juices occasionally.

Once your chicken is fully cooked, let rest for 10 minutes. Slice and serve.

Serve this as a main dish and garlish with some fresh herbs, or slice to add to salads and sandwiches!