Tom Kha Prawn Soup

Ingredients:
For the paste
30g pieces of galangal peeled
2 garlic cloves, peeled
1 stalk of lemongrass, bruised
Small bunch of fresh coriander leaves, chopped and roots reserved
1 medium green chilli, removes seeds first, then roughly chop
3 fresh kefir lime leaves
2 limes
 For the soup:
100ml coconut milk
1 Teaspoon fish sauce
6 tiger or king prawns, shelled and de-veined
50 grams evoke mushrooms
50 grams shimeji mushrooms
100g noodles regular
1-2 limes juice
Salt to taste