"This is very good! It's worth it going to the Thai market to get the extra ingredients. I used to order this at a restaurant and I came home and come up with my own version of it. Everyone loves it that tries it. A lot of ingredients but very easy to make. Serve over rice!"
Place the rice and 2 cups water in a pot, and bring to a boil. Reduce heat to low, cover, and simmer 20 minutes.
Pour the remaining 10 cups water into a large pot, and bring to a boil. Place chicken in the pot. Stir in kaffir lime leaves, lemon grass, green onions, garlic, tomatoes, fish sauce, mushrooms, cilantro, red chile peppers, and tamarind soup base. Cook chicken 30 minutes, or until juices run clear. Remove chicken from pot, debone, and chop. Return meat to the soup, and discard bones. Serve over cooked rice.