Heat the oil in a skillet over medium-high heat. Brown the bratwurst on all sides, about 2-3 minutes per side. Set them aside.
Drain the sauerkraut well and spread it evenly in the bottom of the slow cooker.
Add the sliced onions and smashed garlic on top of the sauerkraut.
Add the bay leaves, mustard seeds, caraway seeds, and brown sugar over the onions and sauerkraut.
Stir the Dijon mustard into the sauerkraut mixture until it’s evenly combined.
Place the browned bratwurst on top of the sauerkraut mixture.
Pour the beer evenly over the bratwurst and sauerkraut mixture.
Cover and cook on low for 6 hours or high for 3-4 hours. Remove the bay leaves before serving. Serve the brats on rolls with the sauerkraut mixture as a topping, if desired. Enjoy!
Video
Notes
If you don’t have caraway seeds, you can skip them or use fennel seeds instead.