Here, dill is used as a herb. Rinse the bunch of dill, trim off the thickest parts of the stalks and spin the herbs dry in a salad spinner or a tea towel. Place them in a blender with 300 ml of the oil and blend for a couple of minutes until the oil is warm, green and free of whole pieces of herb. If necessary, pass the oil through a fine-mesh sieve if you want the mayonnaise to be completely smooth. Now mix the herb oil with the rest
of the oil.
Place the egg yolks in a large bowl together with the mustard, a little salt, freshly ground pepper and 2 tbsp lemon juice, and whisk well using an electric whisk, or if you have a good balloon whisk to make the mayonnaise. Now whisk the herb oil into the egg yolks a little at a time in a thin stream. Pour slowly so 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 thoroughly once more.
Finally, season to taste with salt and, if desired, extra lemon juice; the dill mayonnaise tastes best if it is slightly on the tart side. Transfer the herb mayonnaise to a piping bag.
Refrigerate the mayonnaise immediately, where it will keep for 5–6 days.
