If necessary, defrost the fish and prawns. If you want to prepare a delicious fish stock beforehand, you will find instructions in my recipes.
Clean the spring onions and cut into fine rings together with the greens. Peel the carrots, wash the fennel and cut both into bite-sized pieces. Peel the ginger and garlic and cut into small cubes. Remove the outer, dry leaves from the lemongrass and beat a little with the back of a knife. Squeeze the limes.
Remove the lemongrass. Stir in prawns, a little salt and coconut milk and simmer for another 5 minutes. Season to taste with a little lime juice and, if necessary, salt. Add the fish and turn the stove on to the lowest setting. Let it steep for 10 minutes.
Season to taste and either remove the lime leaves or leave them in the soup for decoration. But they are not eaten. Arrange on plates or in bowls and serve sprinkled with coriander. If you don`t like coriander that much, you can replace it with cress. It tastes very different, but it is also very tasty.