1. To clean, scrub clams with a light brush, and then soak them in 4 quarts of water mixed with 1/3 cup of salt for 15 min. Repeat 2-3 times.
2. For roasted chili paste, in wok heat oil, add shallots and garlic in it. Fry until golden brown. Remove from oil and let it drain.
3. In the same wok, put prawns and chilies. Fry until golden brown. Transfer it to a paper towel and let it drain.
4. In food processor, add dried prawns, garlic, chilies, shallots, and sugar. Blend well.
5. Throw fish sauce, tamarind juice, salt, and fried cooled oil from wok into the processor. Blend to form a paste. Set aside.
6. Place a separate wok on flame, and heat oil in it.
7. Drop clams, and garlic. Stir, and cook until the clams open slightly.
8. Throw fresh chilies, roasted chili paste, and soy sauce. Mix well.
9. Pour chicken stock and stir.
10. Sprinkle with basil leaves, and mix well.