Add wine, paprika, pepper and Dijon mustard to slow cooker. Start cooker on high.
Add beef and mushrooms. Cook on high for 2 hours.
Reduce to low for 30 minutes At this stage you can check you meat and decide if you want to cook it further before adding the other veg. This would depend on the cut used and how tender you want the meat.
Add sweet potato. Cook for another 30 minutes.
Add asparagus and similar amount of green beans. Cook for 30 minutes.
Take out 1 cup of liquid and mix sour cream into it. Mix back into stew.