If needed, pound the chicken breasts to an even thickness.
2 pounds boneless, skinless chicken breasts
Drizzle the chicken breast with olive oil, and then season with kosher salt, black pepper, and garlic powder. Set aside.
1 tablespoon extra-virgin olive oil, 1 teaspoon kosher salt, ½ teaspoon black pepper, 1 teaspoon garlic powder
To make the chimichurri, finely chop the parsley, cilantro, garlic, and oregano or pulse a couple times with a food processor. Just be sure not to puree the herbs.
1 cup packed fresh flat-leaf parsley, ¼ cup fresh cilantro, 4 cloves garlic, 2 tablespoons fresh oregano
Stir in the olive oil, vinegar, salt, pepper, and red flakes, if using.
½ cup extra-virgin olive oil, 3 tablespoons red wine vinegar, ½ teaspoon kosher salt, ¼ teaspoon black pepper, ¼ teaspoon red pepper flakes
Let sit for at least 15 minutes.
Reserve half of the chimichurri. Add the remaining half to a nonreactive container.
Add the chicken and toss in the sauce to coat.
Marinate for at least 30 minutes or up to 8 hours.
To grill, heat grill to medium-high.
Cook chicken for about 7-10 minutes per side, or until it reaches 165°F.
Let rest 5 minutes.
Slice chicken and drizzle with some of the reserved chimichurri.
Notes
Chicken breast: You could also use boneless, skinless chicken thighs if you prefer.
Fresh ingredients: I recommend using all fresh herbs in this recipe. The fresh herbs really bring the most flavor.
Red pepper flakes: They add a bit of heat to the chimichurri. You can omit them or use more depending on your tastes.