Pound the top round to ¼-inch thickness or have your butcher slice to ¼-inch thickness.
Divide the top round into roughly 6x6 or 4x6 portions, then slather each piece of beef with mustard.
Top the beef with the thinly sliced onion and pickles, then top with 2 slices of bacon, leaving about a ¼-inch border.
Roll up each of the pieces of meat into a pinwheel then secure with cooking twine or toothpicks.
Prepare your grill or smoker for direct heat and preheat to 400 degrees. Grill each side of the rouladen for about 3-5 minutes per side. See Note 1
Heat the Dutch oven over medium heat and add a couple tablespoons of cooking oil.
Cook the diced onions for about 3-5 minutes, until softened then add the additional veggies and cook for 3-5 more minutes.
Add in the wine and red wine vinegar and mix well, scraping the bottom of the pan to remove and browned bits.
Add in the bay leaves and bring to a rapid boil then reduce to a simmer. Add in the tomato paste, salt, pepper, and beef broth.
Return to a simmer and return the rouladen to the Dutch oven.
Cook in the oven, grill, smoker, or stovetop at 350 degrees uncovered for 30 minutes.
Flip the rouladen over and cover. Cook for 1 more hour, flipping the rouladen halfway through the cook time.
Remove the beef rouladen from the Dutch oven and strain out the vegetables. Reserve 1 cup of the vegetables and discard the rest.
Add the reserved 1 cup of vegetables to the gravy and use a blender or immersion blender to blend until smooth.
Return the gravy to the Dutch oven and simmer until thickened. See note 2
Taste and salt the gravy as desired.
Remove the twine or toothpicks from the German Beef Rouladen and serve warm, smothered with the gravy.