Heat the butter and oil in a heavy Dutch oven or pot (make sure it's oven-safe if baking in the oven) and generously brown the meat on all sides. Do NOT clean the pan. The beef drippings become the basis for the gravy. Set the rouladen aside on a plate.
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Recipe
Rouladen is a classic German dish that tantalizes the taste buds with its rich flavors and tender texture. Thinly sliced beef is rolled around a savory filling of mustard, bacon, onions, and pickles, then braised to perfection in a robust gravy, creating a hearty and satisfying meal typically enjoyed with mashed potatoes or red cabbage.