Black salsify, or Spanish salsify, is often called poor man’s asparagus. This is slightly unjustified because it tastes good and keeps for a long time. Black salsify is sold with the soil on, so before using it you will need to peel it with a potato peeler and then rinse well with water. Once peeled it will rapidly become discolored, so place it in water until you are ready to use it.
In order to squeeze the bright green juice out of the herbs you should use a wheatgrass press which can be bought in wholefood shops or ordered online.
Boil some lightly salted water.
Cut the black salsify into 6 – 8 in. asparagus-shaped lengths and place them in the water. They will need to boil for 15-20 minutes. During the last four minutes you should allow the broccoli stalks to infuse in the water.
While the salsify is cooking you should prepare the mayonnaise: mix the egg yolk, salt and white wine vinegar in a bowl using a balloon whisk. If you like you can also add a couple of teaspoons of Dijon mustard.
Add one drop of oil and whisk well. Dilute with a bit more oil and whisk again. Continue adding more oil and keep whisking all the time. When the mayonnaise starts to stiffen you can add more generous amounts of oil.
Squeeze the juice out of the herbs using the wheatgrass press and whisk it into the mayonnaise.
Arrange the salsify on plates and cover liberally with the herb mayonnaise.