Prepare the Marinade: In a saucepan, combine equal parts vinegar and water, bringing them to a gentle boil. Stir in your spices and brown sugar, allowing the mixture to simmer for about 5 minutes. Remove from heat and let cool.

Marinate the Beef: Place your beef roast in a large bowl or resealable bag, pour the cooled marinade over it, ensuring the meat is submerged. Seal the container and refrigerate for 3-4 days, turning daily.

Sear the Beef: Preheat your oven to 325°F (163°C). In a Dutch oven, heat oil over medium-high heat. Remove beef from marinade, pat dry, and brown on all sides for about 5 minutes.

Braise the Meat: Add reserved marinade with onions, carrots, and celery. Pour in beef broth to reach halfway up the meat. Cover and braise in the oven for 2.5 to 3 hours until fork-tender.

Prepare the Sauce: Remove beef and strain the cooking liquid. Bring liquid to a simmer over medium heat, reducing until thickened. Add cornstarch mixed with water if desired for extra thickness.

Rest and Serve: Let beef rest for 10-15 minutes before slicing. Serve with mashed potatoes, red cabbage, or spaetzle.