1. Wash and devain 250 gm shrimp.
2. Boil 1.5 litres of water in a pot. once it boils add the thumb sized galangal, 4 stalks of lemongrass, 8 sliced garlic cloves and crushed 8 kaffir lime leaves.
3. Add 2 tbsp thai chilli paste. stir it around and bring the soup to a boil.
4. Add 2 tbsp sugar and 1 tsp salt. let it boil for 2 minutes. then add the thai red or green chillies.
5. Add the devained shrimps, 2 chopped white onions, 2 to 3 handful of mushrooms and 2 sliced tomatoes. cook it for about 5 minutes more.
6. Then add 2 tbsp fish sauce. boil it for another 2 minutes, add 2 tsp lime juice.
7. Cook on high heat for 3 minutes while stirring frequently. add chopped cilantro and serve it hot.