Place pork tenderloins in the bottom of the slow cooker. Add sweet potatoes, carrots, garlic, and mustard seeds.
Sprinkle with thyme, dried onion, salt and Worcestershire Sauce. Add in Lager and beef broth. If the contents are not completely covered add additional beef broth until fully submerged.
Secure lid and cook on high for 4 hours.
Remove pork from crock and let rest on cutting board for at least 5 minutes before slicing into medallions.
Use a slotted spoon to remove potatoes and carrots and add to plate. Place a few slices of pork on top and drizzle with some juice from the crock.