Bring water, lemongrass, galangal and Tom Yum paste to the boil in a pan.
Add coconut cream and onion pieces and simmer for 3 minutes.
Add shrimps or quorn, bring to the boil again and continue cooking until the shrimps are pink.
Add the chilli and tomato pieces, lime juice and fish sauce and continue cooking for another minute.
Turn off the heat and add coriander leaves, spring onions and kaffir lime leaves.
Mix everything well and serve.