Shell shrimps with tail intact. Cut a slit in between and devein. Wash and wipe dry. Slice tomatoes with seeds removed. Scald straw mushrooms. Rinse and cut into halves.
Remove seeds from dried chilli and put it into a wok without oil. Bake for a while. Pat lemongrass until loose and cut into sections. Slice red and green chilli and remove seeds. Wash Laos root. Lemon leave and parsley.
Heat wok with 1/2 tbsp oil. Add shrimp head and shell. Stir fry until red. Add stock and the ingredients in step (2). Boil. Turn to low heat and cook for 20 minutes. Discard the residue. Add tomatoes and straw mushrooms. Boil for 5 minutes. Add shrimp flesh. Allow to boil until cooked. Mix with seasoning. Garnish with parsley.