8sweet rollscut in half to make buns (I used King's Hawaiian)
Place water, sugar, and vinegar in a large slow cooker on high heat. Add brisket and spice packet to mixture. Place potatoes, carrots, onion, and celery on all sides of brisket. Cook on high for 4 hours.
Whisk together both mustards, Guinness, and brown sugar. Set aside.
When brisket is fully cooked, slice into 1/4 inch slices.
Stack 3-4 brisket slices on bottom half of bun, topped with coleslaw. Spread mustard on top part of bun to complete your slider. Serve with the veggie mixture. Enjoy!