I used veal stew meat, and it took a full six hours for it to tenderize. The flavor was excellent, but needed more thyme, salt and paprika. Use full fat sour cream, the low fat doesn't have the right tart flavor. I like a slow cooker recipe that realizes that the meat and veg will make plenty of liquid and the recipe doesn't need two cups of broth to work.
We loved this. I used pork loin instead of veal (chicken would probably work too). I cooked it a bit longer.... Started it on high for about 3 hours, the switched it to low for about 3-4 more hours and it was perfect. Served it over wide Hungarian noodles. It has such a rich flavor! Make sure you whisk the flour mixture thoroughly so there are no doughy lumps. I can't wait fore the leftovers.... And I'll keep my eye out for veal so I can try that too.