Fry the bacon slices in a pan over medium heat until crisp and drain on paper towels. Discard the bacon fat. In the same pan, melt the butter and saute the onions for 5 to 10 minutes. Set aside.

Pound the steaks with a meat tenderizer until they are about 1/8-inch thick, and then sprinkle each steak with salt and pepper. Spread the mustard thickly on the top side of each steak. Place 2 slices of bacon, 2 pickles, and a spoonful of the cooked onions on top of each steak.

Starting from the narrowest end of the steak, roll it up tightly, jelly-roll style, and secure the end with a toothpick.

Heat the olive oil in a heavy saucepan over medium heat, and brown the steak rolls on all sides. Add about 1 cup of water to the saucepan, cover it with a lid, and simmer the steak rolls for 1 hour 30 minutes. Remove the rolls from the pan.

Add the beef broth to the liquid the rolls were cooked in. Boil until the liquid is reduced to one-third of its original amount. Whisk in the half-and-half and tomato paste, being careful not to boil, to avoid curdling. Season with salt and pepper.

Return the steaks to the pan and warm them through in the liquid. Stir in the flour to create a gravy as the meat warms for a few more minutes. Serve the stuffed rolls hot over the spaetzle noodles.