PREPARE GRILL: Preheat your grill or stovetop grill pan over medium-high heat. Lightly brush the grates with extra virgin olive oil. A properly preheated grill means clean char marks and no sticking.
MAKE THE MARINADE: Add 2 whole chipotle peppers from a can, plus 2 tablespoons adobo sauce , 2 teaspoons ground cumin, 1 teaspoon chili powder, 1 teaspoon kosher salt, 1/2 teaspoon fresh ground black pepper, 3/4 teaspoon dried oregano, 2 otablespoons extra virgin olive oil, 1/4 large red onion, roughly chopped , 4 cloves garlic, minced, and 1 fresh lime, juiced to the bowl of a food processor or blender. Process on high speed until a smooth paste forms. You will smell the smoky, spicy aroma immediately.
MARINATE CHICKEN: Place 24 ounces boneless, skinless chicken breasts in a large zip-top bag or shallow dish. Pour the marinade over the chicken and turn to coat each breast completely. The paste will be thick and deeply red. Cover and refrigerate for at least 1 hour, or up to 3 hours.
GRILL CHICKEN: Remove chicken from marinade and discard all remaining marinade. Place chicken on the preheated grill. You will hear a satisfying sizzle as the marinade hits the heat. Grill for 8 to 10 minutes per side, or until the center reaches 165 degrees F.
REST AND SERVE: Transfer chicken to a clean cutting board and rest for 5 minutes. Slice against the grain and serve.
Notes
Make-Ahead: The marinade can be made up to 2 days ahead.Storage: Cooked chicken keeps in an airtight container up to 4 days.Reheating: Reheat in a skillet with a splash of chicken stock over medium heat.Freezing: Freeze cooked chicken up to 3 months. Thaw overnight.Heat Level: Medium spicy. Reduce to 1 pepper for milder flavor.Marinade Safety: Discard all marinade that touched raw chicken.