Dice the fennel into 5 x 5 mm cubes, toss with salt, finely grated lemon zest and lemon juice, then leave to stand for 1 hour to infuse. Bring the apple cider vinegar, sugar, water, bay leaves and peppercorns to the boil, leave to cool, then pour over the salted fennel cubes. Refrigerate overnight.
Rinse the tarragon leaves and pat them dry with a little kitchen roll. Place them in a blender with the oil and blend for a couple of minutes until the oil is green and smooth. Strain the oil through a fine-mesh sieve or a cloth.
Place the egg yolks in a large bowl together with the mustard, a little salt, pepper and 1 tbsp vinegar, and whisk well with an electric whisk, or if you have a good balloon whisk to make the mayonnaise. Now whisk the oil into the egg yolks a little at a time in a thin stream. Pour slowly enough that the oil is constantly being whisked into the egg yolks. Pause occasionally whilst adding the oil and whisk the mayonnaise thoroughly. Continue until all the oil has been added, then whisk in a little water. Whisk thoroughly again – this helps to ensure that the mayonnaise doesn’t separate and that it has a nice, smooth consistency. Finally, season to taste with salt and, if desired, extra lemon juice.
Bring a saucepan of water to the boil. Gently add the eggs and boil them for 9–10 minutes, depending on their size. Then cool the eggs in cold water.
Chop the toasted almonds and finely chop the chives. Slice the raw fennel into paper-thin slices using a mandoline and place them in ice-cold water for 10 minutes. Then spin them dry in a salad spinner and toss with the finely chopped chives. Dice the apple and toss it with a little of the pickled fennel.
Spread the rye bread with a little tarragon mayonnaise, cut the eggs into wedges and place them on the rye bread. Arrange the pickled fennel and apple on top and finally add dollops of tarragon mayonnaise between the eggs. Place the raw fennel on top and sprinkle with toasted almonds and cress.
