Grate enough zest from 1 of the blood oranges to measure 1 tsp. Set aside in a small bowl.
Using a sharp knife, cut the tops and bottoms off the oranges to reveal the flesh. Cut off all the peel so that no white pith remains. Cut the oranges into sections between the membranes. Discard any seeds. Set aside in a separate bowl.
In the bowl containing the orange zest, whisk together the orange juice, vinegar and olive oil. Season to taste with salt and pepper.
Bring a large, shallow pan of salted water to a boil. Add the asparagus and cook until just tender, about 4 - 6 minutes. Remove from the water. Place in a single layer on a serving platter and cool in the refrigerator.
When the asparagus is cool, scatter the orange sections over the asparagus. Drizzle with the vinaigrette. Place the prosciutto strips like curled ribbons over the top of the salad and serve.