Into a large skillet over medium-high heat, add sausage slices in an even layer. Cook until browned on both sides. Remove sausage from pan and set aside. Leave drippings in the pan.
Into the skillet used for the sausage, add onion and saute 2 minutes, to soften. Add garlic and continue cooking an additional 1 minute.
Add white wine, ground black pepper, and fennel seeds. Bring just to a boil then remove from heat.
Into a 6-quart slow cooker, add baby carrots in a single layer.
Add cubed potatoes over the carrots.
Cover the potatoes with sauerkraut.
Over the sauerkraut layer, add the sliced sausage.
Pour wine and onion mixture over the top.
Cover and cook on low for 3 hours, or until potatoes are tender.