Ingredients
For the rouladen

6 thin slices beef round or thin flank steak (about 1 1/2 pounds)
3 medium dill pickle spears
6 slices bacon
1 small white onion, thinly sliced
3 tablespoons German mustard, such as Löwensenf (a good substitute is Dijon mustard) 
Kosher salt
Freshly ground black pepper
For the gravy

2 tablespoons vegetable oil or clarified butter
1 medium white onion, thinly sliced
2 carrots, peeled and roughly chopped
1 tablespoon tomato paste
1 tablespoon flour
1 1/2 cups red wine
1 1/2 cups beef stock
1 tablespoon unsalted butter
1 tablespoon pickle brine (optional)

Ingredients
For the rouladen

6 thin slices beef round or thin flank steak (about 1 1/2 pounds)
3 medium dill pickle spears
6 slices bacon
1 small white onion, thinly sliced
3 tablespoons German mustard, such as Löwensenf (a good substitute is Dijon mustard) 
Kosher salt
Freshly ground black pepper
For the gravy

2 tablespoons vegetable oil or clarified butter
1 medium white onion, thinly sliced
2 carrots, peeled and roughly chopped
1 tablespoon tomato paste
1 tablespoon flour
1 1/2 cups red wine
1 1/2 cups beef stock
1 tablespoon unsalted butter
1 tablespoon pickle brine (optional)
https://www.simplyrecipes.com/german-beef-rouladen-recipe-8401937