1. **Prepare Saffron:** Bloom 1/2 tsp saffron threads in 2 tablespoons of hot water; set aside. 2. **Marinate Barg Kebab:** Slice beef tenderloin very thinly. In a bowl, combine beef with grated onion juice from 1 onion, 1/4 cup olive oil, 1 tsp salt, 1/2 tsp black pepper, and 1 tbsp bloomed saffron water. Mix well and refrigerate for at least 4 hours or overnight. 3. **Marinate Chenjeh Kebab:** Cut lamb into 1-inch cubes. In another bowl, combine lamb with 1/2 of a grated onion, 1/4 cup yogurt, 1/4 cup lemon juice, 1/4 cup olive oil, 1 tsp salt, and 1/2 tsp black pepper. Mix well and refrigerate for at least 4 hours or overnight. 4. **Marinate Chicken Kebab (Joojeh):** Cut chicken into 1-inch cubes. In a bowl, combine chicken with 1/2 of a grated onion, 1/4 cup yogurt, 1/4 cup lemon juice, 1/4 cup olive oil, 1 tsp salt, 1/2 tsp black pepper, and 1 tbsp bloomed saffron water. Mix well and refrigerate for at least 4 hours or overnight. 5. **Prepare Koobideh Kebab:** In a large bowl, combine ground meat with the remaining grated onion (squeezed of excess liquid), 1 tsp salt, 1/2 tsp black pepper, and 1/2 tsp turmeric. Knead vigorously for 10-15 minutes until the mixture is sticky and well combined. Refrigerate for at least 1 hour. 6. **Cook Saffron Rice:** Rinse Basmati rice until water runs clear. In a pot, bring 4 cups of water to a boil with 1/2 tsp salt. Add rice, stir gently, and cook for 5-7 minutes until parboiled. Drain well. In the same pot, melt 2 tablespoons of butter. Add 1/4 tsp bloomed saffron water to a small portion of the drained rice. Layer the plain and saffron rice in the pot. Cover with a lid wrapped in a towel and cook on low heat for 30-45 minutes until fluffy. 7. **Skewer and Grill Kebabs:** Thread the marinated Barg, Chenjeh, and Chicken pieces onto flat metal skewers. For Koobideh, shape the meat around wide, flat skewers into elongated patties. Grill all kebabs over hot coals or a gas grill until cooked through and slightly charred on all sides. Turn frequently to ensure even cooking. 8. **Serve:** Once grilled, gently remove kebabs from skewers. Serve immediately with the saffron rice, topped with a dollop of melting butter. Garnish the platter with grilled tomatoes, slices of fresh red onion, fresh parsley, and a generous sprinkle of sumac.