Trim the asparagus by cutting off the bottom inch on a slight diagonal. Trim off the roots and the top dark part of the leeks; split leeks in half lengthwise. Remove the tough exterior layers. Rinse well.
Place the vegetable stock, leeks and mushrooms in a medium sized pot with a fitted lid. Season with salt and pepper. Bring to a boil, reduce to a simmer, cover and cook for 4 to 5 minutes. Add the asparagus, cover and cook for another 2 minutes. Transfer the vegetables to a plate. Strain the broth into a mixing bowl and mix in the oil and vinegar; season to taste.
Chop up the mushrooms. Peel the eggs and cut into small pieces.
Ladle some of the broth into a serving dish. Layer the vegetables on top and garnish with the chopped egg.
Serves 6