1. Combine the crushed red pepper & ground turmeric in a large bowl and stir in 2 tbs. of hot water. Let stand for 5 minutes. Add the yogurt, olive oil, red wine vinegar, tomato paste, 2 tsp. salt, and 1 tsp. black pepper into spice mixture in bowl. Whisk to combine. Stir in garlic & lemon juice. Add chicken & mix together. Cover and chill for 1 hour.
2. Prepare grill over medium-high heat. Thread chicken pieces onto pre-soaked skewers, dividing equally. Discard marinade in bowl. Sprinkle each skewer with salt & pepper.
3. Grill chicken until golden brown & cooked through, turning skewers occasionally, about 10-12 minutes total. Transfer skewers to platter.
4. Serve with warm pita, tzatziki, labneh, chopped tomatoes, & fresh mint leaves.