Grilled Basil Marinated Chicken

1 Tbs. olive oil
1 Tbs. red wine vinegar
1 Tbs. chopped basil leaves
1 Tbs. finely chopped red onion
2 tsp. kosher salt
1 tsp. whole black peppercorns
1 clove garlic, chopped
4 boneless, skinless chicken breast halves (about 2 pounds)

Whisk together the oil, vinegar, basil, onion, salt, peppercorns, and garlic in a bowl. Transfer the marinade to a gallon-sized sealable plastic bag with the chicken and shake to combine. Refrigerate at least 3 hours and up to 12 hours. Remove chicken from the marinade. Grill the chicken, turning once, until browned and just cooked through, about 4 minutes per side.