Rouladen are a true indulgence that requires patience, but the result is well worth it. Although filled with simple ingredients, their combination creates a complex flavor. They are traditionally served with dumplings or boiled potatoes, topped with the rich gravy from the braising process.
Gently pound the beef slices to tenderize. Season both sides with salt and pepper. Spread one side with a layer of mustard.
On the mustard-coated side, place a slice of bacon, a quarter of a pickle, and a piece of onion. Carefully roll the meat into a tight roll. Secure the rolls with kitchen twine or toothpicks to hold their shape.
In a large pot or Dutch oven, heat the oil and sear the rolls on all sides until browned. Remove them from the pot and set aside.
Add the chopped onion, carrot, and celery to the same pot. Sauté until the vegetables are browned and have released their flavor. If needed, deglaze with a little water. Return the rolls to the pot.
Pour in the wine, letting the alcohol evaporate, then add the beef broth. Ensure the rolls are almost fully submerged in the liquid. Bring to a boil, then reduce the heat, cover, and simmer for 2.5-3.5 hours, or until the meat is very tender.
Once the rouladen are done, remove them from the sauce and remove the twine/toothpicks. You can strain the sauce with the vegetables through a sieve or use an immersion blender to make it smooth. If the gravy is too thin, you can thicken it with a little flour mixed with water.
Return the rolls to the gravy, heat them briefly, and serve. They are traditionally served with potato dumplings, mashed potatoes, or spaetzle, and red cabbage.