Step 1

Place chicken breasts between two sheets of plastic wrap and pound to an even thickness. Trim off fat.

Step 2

Make the marinade by whisking together lemon juice through red pepper flakes. Place chicken in a plastic bag and pour over marinade. Massage so all chicken is covered in marinade. Place in refrigerator for a few hours or overnight.

Step 3

Mix together all tzatziki sauce ingredients and set aside.

Step 4

Grill chicken about 6-8 minutes per side or until a meat thermometer reads 160º. Remove from grill and place under foil to rest.