Fill the rouladen: Lay out the beef slices, season both sides with salt & pepper, spread each with mustard, add bacon, pickle strips & onions, roll tightly and secure.
Brown: Heat clarified butter or oil, brown rouladen deeply on all sides (very important!), remove rouladen.
Start the sauce: Sauté onion, carrot & celery, add tomato paste (+ sugar) and roast 1–2 minutes, deglaze with a little broth first, reduce, repeat, add remaining broth + water + bay leaves, return rouladen to the pot.
Braise: Cover and simmer gently 1.5–2 hours, take rouladen out.
Finish the gravy: Blend the sauce (or press through a sieve – very traditional), reduce until thick and glossy, season, return rouladen into the sauce.
