Bring 2 quarts of water to a gentle boil. Carefully lower quail eggs into the water; cook for 2 1/2 minutes. Remove and shell immediately.
Add mustard, sherry vinegar and whole egg to the bowl of a food processor fitted with the metal blade. Blend for 3 seconds. In a cup with a spout, mix the 2 oils. With the motor of the food processor running, add the oils in a thin stream. Mayonnaise should thicken after about 3/4 of the oil has been added. Season with salt and pepper.
Let eggs come to room temperature. Place ham slices on 6 small plates and spread 1/6 of mayonnaise over each slice. Cut eggs in half and place 3 halves on each plate. Garnish each egg with a small piece of black olive, and garnish each plate with 3 asparagus tips.
If quail eggs are unavailable, the smallest chicken eggs that you can find are a good substitute. Hard-boil them, and proceed as with quail eggs. Serrano ham is available in Latin markets, prosciutto is a good substitute.
Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.