1In a small bowl, use a pastry blender or fork to combine the flour and butter; set aside.
2Heat oil in a large skillet. Brown veal, a few pieces at a time, in hot oil. Using a slotted spoon, remove browned veal from skillet; place in a sieve over a medium bowl to drain; set drippings aside.
3Add onion to the oil in skillet; saute until transparent. Add mushroom; saute until tender. Add wine and half and half; stir in flour mixture. Simmer 3 to 4 minutes, stirring constantly, until slightly thickened. Season with salt and pepper. Stir in the drippings from the veal and the browned veal. Heat through.
4To make rosti:
Boil or bake potatoes until about half cooked. Slice hot potoates.
5Melt lard in large skillet. Add potato slices. Cook until potatoes soften and form a golden crust. Serve veal mixture with rosti.