Boil 2l of water.

Squeeze lime juice

Strip outermost layer of Lemongrass stalks, pound with mallet and slice into 1in length

Chop galangal, and peel garlic

Tear the kaffir lime leaves

Take off the stalks from the chili and cut them in 2 pieces

Throw the Lemongrass, galangal, kaffir lime leaves, garlic, and chili into the boiling water

After 10 minutes, toss in your meat of choice and put fire to low

Cut the oyster mushroom, onions and tomatoes into big chunks and toss them into the water

Boil for about 2-3 minutes

Add 6tbsp fish sauce and 2tsp sugar, boil until mushrooms and onions are soft

Turn off heat and add lime juice. Adjust taste with more fish sauce/sugar/lime juice depending on preference

Add cilantro and serve