Zest one lemon, juice both lemons, and finely mince the garlic cloves.
Add the lemon juice, lemon zest, extra virgin olive oil, red wine vinegar, garlic, oregano, kosher salt, and black pepper to a medium bowl.
Add the Greek yogurt for a creamier marinade and crushed red pepper flakes for a little heat, if desired.
Whisk thoroughly until the ingredients are combined and the mixture looks slightly emulsified.
Place 1½–2 pounds of chicken in a food-safe container or resealable bag.
Pour the Greek Chicken Souvlaki Marinade over the chicken and turn the pieces until evenly coated.
Seal the container and refrigerate for at least 2 hours, preferably 4–6 hours.
Remove the chicken from the marinade and discard any marinade that has been in contact with raw chicken.
Thread cubed chicken onto skewers and grill until browned, juicy, and cooked through to a safe internal temperature of 165°F (74°C).
Notes
Chicken breast or boneless, skinless chicken thighs both work well with this Mediterranean chicken marinade. For especially tender chicken with a slightly creamy coating, include the optional Greek yogurt.