1In a large saucepan, combine prawn heads, stock and lemongrass. Bring to boil on high. Reduce heat to low and simmer 10 mins. Strain liquid into a large bowl, discarding solids. Return drained stock to same pan.
2Stir in tomatoes, kaffir lime leaves and chilli. Simmer 4 to 5 mins.
3Add prawns to stock. Simmer, 1 to 2 mins, until prawns change colour. Remove from heat. Stir in sauces, juice and gula melaka to taste. Serve topped with snow-pea shoots and carrot.