In a medium bowl, whisk together balsamic vinegar, olive oil, minced garlic, Dijon mustard, dried oregano, salt, and black pepper.
Place the chicken pieces in a resealable plastic bag or a shallow dish. Pour the marinade over the chicken, ensuring all pieces are coated.
Marinate in the refrigerator for at least 30 minutes, or up to 4 hours. For longer marination, consider using a less acidic liquid or reducing the marination time to prevent the chicken from becoming mushy.
Preheat your grill or oven to 400°F (200°C).
Remove chicken from the marinade and discard the excess marinade. Grill or bake the chicken for 20-25 minutes, or until the internal temperature reaches 165°F (74°C) and the juices run clear.
Let the chicken rest for 5 minutes before serving.
Notes
This marinade is versatile and can be used for chicken thighs or breasts. Adjust marination time based on your preference and chicken cut.