• Lay the beef slices out flat. Spread with about 2 tsp of mustard each and sprinkle with salt and pepper. Place a strip of bacon on each so its running the length of the beef.
• Place the sliced pickle, carrot, and onion together towards one end of each slice. Roll the beef slices up over the veggies, rolling and tucking in the ends as you go. Secure the rolls with a toothpick.
• Preheat oven to 325℉. Heat oil in a Dutch oven or cast iron over medium high heat. Add beef rolls and generously brown on all sides, about 3 - 5 minutes. Remove from the pan.
• Add the butter, onion, celery, and carrot to the pot. Season with salt and pepper. Cook until slightly softened, about 5 minutes. Add garlic and cook for another minute until fragrant.
• Pour in red wine, scraping up the browned bits. Bring to a rapid boil and reduce heat to simmer for 2 minutes. Add tomato paste, broth, sugar, salt, pepper, and the bay leaf. Bring to a simmer and nestle rouladen back into the dish.
• Bake in oven for 90 minutes, or until fork tender.

For the Gravy

• When the beef is tender, remove from the dish. Pour the liquid through a strainer and reserve the liquid. Return the liquid to the pot and simmer.
• Mix 1 - 2 tbsp of cornstarch (depending on how thick you want it) with 2 - 3 tbsp of the liquid in a small bowl. Add to the pot and stir to combine. Once simmering, reduce the heat to low to thicken. Taste and adjust seasoning as needed.