Remove the heads and tails of half the prawns and the heads only of the other half.
Peel and devein the prawns, then chop the ones with no tails into small chunks
If necessary, peel the chorizo and chop into chunks
Crush the garlic and finely slice the fennel
Chop the tomatoes into chunks
Heat a pan of water to boiling, then add the pasta and cook until al-dente following the packet instructions
Meanwhile, heat the oil in a large, deep frying pan.
Add the garlic and fennel. Season well with salt and pepper
Cook over a medium heat until the fennel is translucent and starting to caramelise (this should take around 5 minutes). If you are not using fennel, just cook the crushed garlic for a minute or two
Add the chorizo to the pan and cook for a few minutes till the fat starts to run.
Add the wine and reduce down.
You can keep this mixture warm on a low heat until just before the pasta is cooked
3 minutes or so before the pasta should be ready, add the prawns. Cook over a medium heat, turning frequently. Add the tomatoes after a minute and squeeze in the fresh lemon juice. Season with salt and pepper
Drain the pasta, reserving a little of the water for the sauce
Add the pasta to the pan, together with the pasta water. Stir well and remove from the heat
Check the seasoning and serve garnished with fennel fronds or your choice of fresh parsley or rocket (arugula)