1Add chipotle peppers in adobo, minced garlic, chopped red onion, lime juice, olive oil, Mexican oregano, chili powder, cumin, salt and pepper to a food processor and blend until smooth.
2Poke holes in chicken breasts with a fork.
3Add chicken to a ziploc bag and pour marinade over it.
4Refrigerate for at least one hour.
5Cook chicken for 8–10 minutes per side until the internal temperature reaches 165°F (74°C).