In a large saucepan over medium/medium-high heat, melt the butter.
When no longer foaming, add the carrots, celery, and onions.
Cook vegetables for 1 - 2 minutes, adding a little salt and a few grinds of black pepper.
When the onions have softened slightly, add the garlic and spices, cooking until fragrant, approximately 1 minute.
Add the beef stock/broth and potato, stirring to combine and bring to a steady simmer.
Reduce heat to a low simmer and cover, checking occasionally.
Cook for 2 - 3 hours until potatoes are tender and flavors are melded.
Add the cubed sauerbraten and gravy, stirring to combine.
Simmer to heat the beef through, then taste and add salt and pepper as needed.
Notes
This stew can be based on your own combinations of vegetables - onions, celery, carrots, potatoes, corn, peas, etc. If using frozen peas or corn, add them at the end when adding the beef to heat through.
Recipe by Cooking 4 One at https://www.cooking-4-one.com/2017/02/08/sauerbraten-stew/