Low carb and Atkins friendly, this keto beef brisket will be a hit with the entire family! Dairy free, nut free, egg free too. Rub brisket on all sides with bbq seasoning. Heat oil in Instant Pot on Saute function. Place the seasoned brisket into the pot and sear for 3 minutes per side.
Place brisket, fat side up, in the slow cooker. Spread the dijon mustard over the top of the brisket and sprinkle remaining 1/3rd of onion mixture over the top. Set slow cooker on low for 9 hours. When brisket is cooked, carefully remove it from the slow cooker and place it in a large roasting pan.
Place the brisket in a large bowl and cover the top and bottom with 2/3rds of the onion mixture. Place brisket, fat side up, in the slow cooker. Spread the dijon mustard over the top of the brisket and sprinkle remaining 1/3rd of onion mixture over the top. Set slow cooker on low for 9 hours.
Light charcoal and preheat barbecue cooker to 225°F. Place the brisket on cooker using indirect heat (not directly over the fire) with fat side up. Cook for 7–8 hours until the internal temperature of the brisket reaches 160–170°F. Add wood chips during the initial cooking process to increase smoke flavor.