Fill the kettle and boil it. Trim the courgettes. Use a spiraliser, julienne cutter or vegetable peeler
to cut long thin strips from each courgette, turning the courgette as you go, peeling strands from each side till you’re left with a seeded core.
Put the courgette strips into a heatproof bowl. Cover them with hot water from the kettle. Cover with cling film. Set aside. Trim the end and any dry tips from the fennel. Halve it and slice very thinly.
Peel and crush or grate the garlic. Halve the chilli. Flick out the seeds and white bits for a milder flavour. Finely slice it. Finely grate the zest from the lemon. Juice it. Halve the cherry tomatoes.
Heat 2 tbsp olive oil in a large frying pan. Add the fennel. Stir-fry for 2-3 mins till it’s just starting to soften and colour.
Add the garlic, chilli and lemon zest to the pan with the cherry tomatoes. Stir-fry for 2-3 mins till the tomatoes are beginning to soften. Take off the heat. Pop on a lid.
Pour the lemon juice into a small pan. Add the crab. Warm over a medium heat for 1-2 mins till piping hot.
Remove any thick stalks from the watercress. Roughly chop. Drain the courgetti. Mix the watercress and courgetti into the fennel. Warm through for 1-2 mins.
Season the courgetti with a little salt and pepper. Divide between two warm plates. Top with the hot crab and serve.