In a large bowl combine the 3 tablespoons Aleppo pepper with 2 tablespoons warm water. Stir and let sit for 5 minutes for the water to be absorbed. (if using red pepper flakes and paprika, combine 4 teaspoons of each in the bowl with 4 tablespoons warm water)
Add the next six ingredients to the bowl: Yogurt, oil, vinegar, tomato paste, salt, and pepper. Stir thoroughly to combine.
Next mix in the garlic and lemon slices. Add the chicken and stir to fully combine all ingredients.
Cover bowl with plastic wrap and chill for at least an hour (and up to a day)
Preheat the barbecue to medium-high heat. Rub oil over the grates. Sprinkle chicken with salt and pepper. Grill the chicken about 6 minutes per side, or until cooked through.