Filet the top round to a ½" thick. Cut the beef into rectangles approximately 3x4 inches. Pound each rectangle to roughly a ¼" thick which will make them substantially larger. You should have 8-12 pieces. Note: Your butcher might be able to slice the beef for you.
In a large oven safe pan or Dutch oven over medium heat, saute the bacon about halfway then remove the pieces to a paper-towel lined plate. Remove a few tablespoons of the bacon fat and save for later.
Add the onion, carrot, and celery and saute until soft (about 10 minutes). Remove the pan from the heat. Place the vegetables in a bowl and set aside.
Arrange the pounded meat on a cutting board and season the with salt and pepper. Spread a thin layer of mustard onto each piece. Evenly divide and spread the filling onto each piece, making sure to add an equal amount of bacon. Place a pickle slice onto each piece.
Roll each piece tightly and secure them with toothpicks or kitchen twine.
Heat a large pot or pan to medium heat with the saved bacon fat. Sear the pieces on all sides, working in batches if required to not overcrowd the pan. Set the seared rolls aside and prepare the sauce.
Preheat oven to 325f and set the rack to the middle level.
Heat the same pan/pot to medium heat and add a few tablespoons of olive oil or lard then the tomato paste. Saute for a few minutes, adding a splash of water if it starts to burn. Add the flour and cook for a minute or until no white specks appear.
Add the wine and and beef stock and turn the heat to high. With a wooden spoon while scrape the bottom of the pan to remove any brown bits.
Once simmering, add the beef rolls to the pot and cover with a tight fitting lid or foil. Place in the oven. Note: you can simmer over very low heat on the stovetop if you like.
Cook for 60 to 90 minutes, or until fork tender.
Once tender, remove the rouladen from the sauce and remove the toothpicks. Taste the sauce and season with salt and pepper. Serve with spaetzle or mashed potatoes. Enjoy! Note: if the sauce isn't thick enough, remove the rouladen to a platter and place the pan on a burner over medium-high heat. Whisk in a cornstarch slurry and thicken to your liking. You shouldn't need more than 2-3 teaspoons of cornstarch.
Oma's recipe: 6 beef roladen from butcher, 6 slices bacon, ¾c + ¼c chopped onion, dijon mustard, ½c red wine, 2 beef boullion, S&P, bay leaf, shake of ground cloves, 3 Tbsp + 1 tsp flour, 1.5c water to dissolve boullion. Cook bacon in microwave. Spread mustard thinly on Roladen meat and top with one slice of bacon on each Roladen. Saute ¾c onion in a little oil for 5min over medium. Divide onion among the Roladen and roll up. Fry in a little oil till nicely browned. Take out of fry pan and add a little more oil and fry rest of onion 2-3min until light brown. Add flour, stir over med heat for 1min. Add beef broth, wine, S&P, cloves, and bay leaves. Bring to boil, then reduce heat, cover and simmer 1.5hr. Can be made ahead and reheated
