Boil 750mL water in a pot.
Cut chicken, mushroom, tomato, and onion into cubes.
When the water starts to boil, add the Thai herb and spices, and let it cook for 5 mins.
Add the chicken and vegetables to the pot and cook for 5-10 mins, until it starts to boil.
Make sure the water is not boiling, add the coconut milk, keep stirring gently. (Coconut milk is delicate, handle with care!)
Add some fish sauce and lime juice. You can taste and adjust by adding more coconut milk/fish sauce/lime based on your liking. Once you reach the taste that you like, you are done, add some coriander on top if you like!