1. Brown veal in butter in a skillet; set meat aside. Saute onion in same skillet until golden.
2. Add beer, bay leaf, salt, and pepper. Cover and simmer 15 minutes.
3. Transfer veal and onion to a platter. Make a paste of flour and a little water; stir into cooking liquid in skillet. Cook, stirring constantly, until thickened and smooth. Pour over veal and onion.