Mexican crab mayonnaise

When I was very little we would sometimes go to stay with my grandparents on our own; when we were good they would take us out for lunch in a restaurant. There was almost always prawn cocktail on the menu and it was my favourite thing in the world (it was pink; I had a thing for pink). I created this recipe in remembrance of those exciting prawn cocktail moments, using crab instead of prawns. Both kitsch and modern, this starter is a winner at the height of summer when crab is at its sweetest. FEEDS 4 FOR THE CRAB 2 chipotle chillies 2 medium egg yolks 1 tsp Dijon mustard 400ml mild olive oil juice of 1 lime, plus extra to taste 1½ tbsp tomato ketchup, plus extra to taste ½ tbsp Worcestershire sauce, plus extra to taste 250g fresh white crab meat FOR THE SALAD 1 apple, finely sliced 1 fennel bulb, outer layer removed, finely sliced squeeze of lemon juice 55g watercress juice of 1 lime extra virgin olive oil 2 avocados

Snip the chillies open, discarding the stalk and seeds. Place a dry pan over a medium heat and, when hot, add the chillies, gently toasting each side for a couple of minutes until they begin to smell fragrant; take care not to burn them. Cover in boiling water and simmer for 15 minutes to soften. Meanwhile prepare the apple and fennel for the salad and place in a bowl of iced water with a squeeze of lemon juice (to get ahead you can do this an hour or so before you eat).

Drain the chillies, setting aside the water, and transfer to a food processor. Whiz until puréed, adding a dash of the chilli water to loosen if necessary, then add the egg yolks, mustard and a pinch of salt. With the motor running, very slowly start to drip the oil through the funnel of the processor until the mayonnaise starts to thicken and emulsify, then pour in the remaining oil in a thin stream. Stir in the lime juice, ketchup and Worcestershire sauce and season to taste.

Stir together equal quantities of the mayonnaise and the crab (the remaining mayo will keep in the fridge for at least a week). Add more lime, ketchup or Worcestershire sauce to taste; it should be smoky and tangy but with the crab flavour shining through.

Drain the apple and fennel and pat dry. Add to a bowl with the watercress, a few squeezes of lime juice and some olive oil and season with salt and pepper. Toss and transfer to plates. Halve, pit and peel the avocados, then place half an avocado on each plate. Spoon the crab mayonnaise over the avocados and serve.