Make spice paste; place lemongrass and roots in a mortar and crush to a paste with pestle. Add ground turmeric, ginger, cumin, brown sugar, garam masala and fish sauce. Grind to combine.
2
Heat oil in saucepan over medium-high heat. Fry paste for 2 mins until fragrant. Stir in onion and cook for 3 mins. Add coconut milk and fish stock and let it stir 7-8 minutes.
3
Gently lay fish into sauce and add kale. Squeeze over some lime and poach the fish in the sause until its tender. Top the soup with some spring onions, fresh coriander, some chili flakes and a little spoon of Crème fraîche.