Heat 1 tablespoon of oil in a skillet over high heat. Brown the brisket on both sides and transfer to your slow cooker.
Add another tablespoon of oil and sauté the onions until soft, about 4 minutes. Add the garlic and cook 2 minutes more.Add beef stock, honey, mustard, ketchup, vinegar, and Red Boat. Heat and stir and season with smoked paprika, salt, and pepper.Pour sauce over the brisket in the slow cooker.
Cover and cook for 8 hours on LOW or 4 to 5 hours on HIGH, until the meat is fork-tender.
Remove the meat to a cutting board and slice it thinly against the grain.
Skim fat from the cooking juices. Transfer to a saucepan and reduce for about 10 minutes. Spoon over the sliced meat and serve.
If you’re following a low-carb way of eating, sweeten with stevia and swap out the ketchup for tomato paste instead. It's still a delicious sauce. Promise.