Grilled Chicken Breasts with Chimichurri Sauce

Steps

1. Cut each chicken breast horizontally into 2 thin cutlets. Place chicken between sheets of plastic wrap and, using a meat mallet, pound chicken to ⅓-inch thickness. Add the buttermilk to a medium bowl and season with salt and pepper. Add chicken to coat in buttermilk. Cover bowl with plastic wrap and refrigerate for at least 2 hours and up to 2 days.
2. Set grill to medium-high and remove chicken from marinade. (Discard marinade.) Finely chop the herbs. In a bowl, combine the garlic, oil, and herbs. Finely chop the jalapeño and stir into chimichurri. Season with salt and pepper.
3. Lightly brush grates with oil. Transfer chicken to grill and season with salt and pepper. Grill chicken 4–5 min. per side, until an instant-read thermometer reaches 165°F. Halve the lemon and grill, cut-side down, 3 min., until charred and heated through.
4. Transfer chicken to a plate. Squeeze juice from 1 charred lemon half into chimichurri. Squeeze remaining lemon half over chicken. Slice chicken and serve with chimichurri.