Preparation

• 1
  Separate the white from the yolk of the egg, discard the white and whisk the yolk in a small bowl.
• 2
  Peel and crush the garlic and add to the egg yolk. Add the finely grated zest of half the lemon and 2 teaspoons of lemon juice. add the mustard and whisk together.
• 3
  Add the oil [I used sunflower but you can use olive or vegetable oil] just a few drops at a time, whisking briskly and continually as you do so. Add as much as you need to make an aioli that is really smooth and quite thick.
• 4
  Stir in a pinch of salt to taste. Cover the bowl of aioli with clingfilm and leave to chill in the fridge.
• 5
  Deseed the cucumber and peel it if you like; I prefer it with the skin on. Slice it into very thin long strips.
• 6
  Split and toast the bagels. Spread some aioli on the bottom piece of each bagel then carefully place crab on top of it, sharing the dressed crab between the two bagels. Drizzle with more aoli, scatter on strips of cucumber and put on the bagel top.
• 7
  Serve with a garnish of dressed salad leaves, such as baby spinach, rocket and lambs lettuce, and the remaining half a lemon cut into wedges.