Assam curry prawns

Ingredients

• 500 g jumbo prawns
• fresh curry paste
• 3 stalk of lemongrass
• 1 ginger bud
• 5 Kaffir lime leaves
• 1 tomato
• 1 Japanese cucumber
• 1 onion
• cooking oil
• 50 ml water
• light soy sauce to taste
• brown sugar to taste
• a ping pong - sized of tamarind pulp with 200 ml of water