Prepare the Marinade: In a mixing bowl, combine ½ cup of plain yogurt, ½ cup of fresh lemon juice, 3 tablespoons of vegetable oil, 2 tablespoons of tomato paste, 1.5 tablespoons of yellow mustard, 1 tablespoon of minced garlic, and a sprinkle of your spices including 1 teaspoon of white pepper, ½ tablespoon of sumac, 1 teaspoon of paprika, 1 teaspoon of red chili powder, 1 teaspoon of black pepper, and ½ tablespoon of salt. Whisk until the marinade is smooth and well-blended.

Cut Chicken: Take 2.2 pounds of boneless, skinless chicken breasts or thighs and cut them into even 1-inch cubes. Once cut, place the chicken in a large bowl, making it ready for marination.

Marinate Chicken: Add the cubed chicken into the bowl with the yogurt-garlic marinade, ensuring each piece is coated. Cover the bowl and refrigerate for at least 4 hours, ideally overnight.

Skewer Chicken: Soak wooden skewers in water for at least 30 minutes. Thread 5-6 pieces of marinated chicken onto each skewer, leaving space between pieces.

Grill Chicken: Preheat your grill to medium heat (about 350°F/175°C). Place the skewers on the grill and cook each side for approximately 5 minutes, ensuring the internal temperature reaches 165°F (75°C).

Rest & Serve: Remove skewers from the grill and let them rest under foil for about 10 minutes. Serve with pita bread, garlic sauce (toum), and pickled vegetables.