Choose small red onions for roasting as you really want the finished leaves to be bite-sized. The smoked eel can be replaced with smoked salmon or mackerel.


Makes: Approximately 20 pieces or bites

  • 4 small red onions
  • 1 tablespoon olive oil
  • sea salt and freshly cracked black pepper
  • 250g (9oz) smoked eel cut into dice or thin slices 
  • 5 tablespoons horseradish mayonnaise (see recipe)
  • sprigs of chervil or watercress for garnish

Horseradish Mayonnaise

  • 2 egg yolks
  • 2 tablespoons of Dijon mustard
  • 1 tablespoon of caster sugar
  • 2 tablespoons of wine vinegar
  • 150ml sunflower oil or light olive oil or a mixture of both oils
  • 1 heaped tablespoon of finely, grated fresh horseradish
  • 1 teaspoon of chopped tarragon


  1. Preheat oven to 200°C/400°F/Gas Mark 4.
  2. Cut the unpeeled onions in half straight down through the middle and through the root. Brush the cut surfaces with olive oil and place cut side down on a roasting tray.
  3. Cook for 20-40 minutes or until the onions feel completely tender. Remove from the oven and allow to cool.
  4. When the onions are cool, separate the layers of onion to achieve little cup-shaped leaves. These can be prepared in advance and stored at room temperature. 
  5. To assemble, place the onion leaves on a serving dish. Spoon a little of the horseradish mayonnaise into the base of each leaf and follow with a piece of eel and a spring if chervil or watercress.

Horseradish Mayonnaise

  1. Put the egg yolks, mustard, sugar and vinegar in a bowl. Whisk well and add the oil gradually in a slow and steady stream while whisking all the time. The sauce will emulsify and thicken quite easily.
  2. Add the horseradish and chopped herbs. Taste and correct seasoning. It is unlikely to need salt because of the large quantity of mustard.
  3. Chill until needed.