2 tablespoons Dijon mustard

1 teaspoon red pepper flakes

For the brine:

2 tablespoons kosher salt

4 cups water

4 boneless, skinless chicken breasts (about 2 pounds total)

Make the marinade. Whisk all the ingredients together in a small bowl; set aside.

Make the brine. Place the salt and water in a large (gallon-sized) zip-top bag, and stir until the salt is dissolved. Add half of the marinade, and stir to combine. Reserve the remaining marinade in the bowl for glazing the finished chicken.

Pound the chicken thin. Working with 1 chicken breast at a time, place a breast inside a gallon zip-top bag. Use the flat side of a meat mallet or rolling pin and pound until 1/4-inch thick. Set the flattened chicken breast aside and repeat with remaining breasts.

Marinate the chicken. Place the chicken in the zip-top bag with the marinade and brine, and massage to coat. Seal the bag, and place on a baking sheet. Arrange the chicken so it is sitting in a single layer in the bag. Refrigerate at least 30 minutes or overnight.

Prepare the grill. Prepare an outdoor grill for both high direct and indirect heat. Scrape any debris from the grill grates and oil well.

Pat the chicken dry. Remove the chicken breasts from marinade, and pat dry with paper towels.

Grill over direct heat. Place the chicken breast over direct heat, with the grill's grates running at an angle against the width of the breast. For the best grill marks, don't move the chicken once it has been set down and avoid pressing, prodding or poking for 3 minutes. Flip the chicken -- when ready, the breasts will lift up easily for flipping. Cook the second side until grill marks appear, about 3 minutes more.

Grill over indirect heat. Move the chicken to indirect heat (or reduce the heat to medium on a gas grill). Brush with the reserved glaze. Check the chicken for doneness with a digital probe thermometer. The chicken is ready when it registers 165 F. Brush with more reserved glaze, if desired.

Rest the chicken. Transfer the chicken to a clean cutting board or serving platter and let rest 5 minutes. Slice if desired.

Recipe notes: Leftovers can be stored in an airtight container in the refrigerator for up to four days.

(Meghan Splawn is associate food editor for TheKitchn.com, a nationally known blog for people who love food and home cooking. Submit any comments or questions to editorial@thekitchn.com.)