Step 1 Blanch the asparagus in boiling, salted water until just cooked (but still slightly crunchy), about 3 minutes for medium spears.
Step 2 Salt the veal slices. Place the flour in a shallow dish; stir in 1 teaspoon salt and one-eighth teaspoon white pepper. Dredge the veal in the flour and shake off any extra flour.
Step 3Wrap each veal slice around 1 mozzarella slice and two asparagus spears.
Step 4Heat a large saute pan over medium heat. Add 2 tablespoons butter, and when melted add the rolled veal slices. Saute for 45 to 60 seconds until veal is cooked through, then remove from the pan and reserve in a warm place.
Step 5Place the remaining tablespoon of butter in the hot pan, and add the mushrooms. Cook over high heat until lightly browned, about 1 1/2 minutes, then deglaze the pan with the wines and bring to a boil.
Step 6Let the liquids reduce by half before adding the veal demi-glace. Reduce the sauce again by half. When finished, season with one-half teaspoon salt, or to taste. You will have about 1 cup sauce.
Step 7Serve each portion of veal scallopini with one-fourth cup sauce.