Braised Beef Rolls (Rinderrouladen)

This is my favorite recipe that my German mother-in-law cooked and we have many fond memories of having it on special occasions. I was nervous about getting the meat correctly sliced by the butcher, but found a package in the store that was perfect. I opted not to use a recipe in another German cookbook, because it was too simple. This has a lot of variations, we make ours with spreading mustard on the beef and adding a piece of pickle before rolling and browning. The best part is the gravy! It is important to cook them long enough that they are tender, but not so much that they fall apart. The best part is the gravy!