Peel and boil the asparagus. Dice the breast of duck, and thread the pieces into four skewers, sprinkle with coarse salt and the spices and marinate them for a few hours.
Process the yolks in a mixer with extra virgin oil until smooth. Season with salt.
Wisk the herbs in extra virgin oil.
The oil obtained can be preserved in a fridge and is excellent for many recipes.
Cook gently on the grill the duck skewers, place the green and white asparagus and a skewer on a plate, garnish with the egg cream and complete with the herb oil.