Clear tomato soup with freshwater crayfish and wild fennel

Serves 4-6

Break the jelly up a little then spoon into serving bowls and scatter on the crayfish and fennel (Jason Lowe)

You might imagine this is a tricky dish to execute, but it's simple, really. This year, I've discovered a regular supply of crayfish on a stretch of the River Kennet. I was starting to worry that my campaign to cull the signal crayfish (which, since its introduction to British waters has threatened to wipe out our native species) had gone a bit too far, but sure enough there are still plenty around to enjoy.

You can also serve this soup with crab, lobster or simply some diced-up tomatoes.

1.5kg ripe tomatoes, halved
2 cloves of garlic, blanched in water for 2 minutes
300ml good-quality tomato juice
A few sprigs of basil
Salt and freshly ground black pepper
3 leaves of gelatine (9g)
1kg live freshwater crayfish
1tbsp fennel seeds
A few sprigs of wild fennel or dill

Coarsely blend the tomatoes, garlic and basil in a food processor with some freshly ground black pepper and salt and 250ml of the tomato juice.

Line a colander with double muslin or a clean tea towel and rest over a large bowl. Pour the tomato pulp in and put in the fridge overnight. The next day you should have about 600-700ml of clear juice; gently squeeze the pulp to extract as much juice as possible.

Soak 3 leaves of gelatine in cold water until soft. Meanwhile, remove a small ladleful of the clear tomato juice and heat in a pan. Squeeze the water from the gelatine leaves and stir them into the hot tomato juice until dissolved. Don't boil it. Add this to the rest of the juice, add the remaining tomato juice, stir well and put in the fridge for 1-2 hours until set.

Meanwhile, bring a pan of water to the boil with the fennel seeds and plenty of salt and plunge in the crayfish; bring to the boil, simmer for 3 minutes, then drain in a colander and leave to cool. Carefully peel the tails and crack the claws if they are large. Don't throw the shells away as they will make a good bisque.

To serve, break the jelly up a little then spoon into serving bowls and scatter on the crayfish and fennel.