Whisk the egg yolk with the vinegar until it thickens, and then very slowly add the oil drop by drop at first. Once you have added half the oil, you can add it slightly faster. The mayonnaise will thicken and become creamy.
Cut the asparagus spears into one inch pieces and cook in boiling water for 3-4 minutes. Remove them to the ice bath to halt the cooking process. Reserve the cooking water and 10 of the asparagus tips to use as a garnish.
Blend the remaining asparagus spears in a liquidizer with the dill, using a little of the cooking water to help get it going if needed. We need the asparagus puree to be very smooth. Season with salt and pepper.
Add three tablespoons of water to a small glass or jug and pour the powdered gelatin into it. Place the glass or jug into a saucepan with a small amount of hot water to help the gelatin powder dissolve into the water.
Fold the whipped cream and then the meringue into the asparagus mousse mixture until it is fully combined. You may need a pinch more salt as cream always impacts the salt levels of a dish