To prepare the Beef Brisket (3 pound), slice away the thicker pieces of fat. Make sure to leave some fat on the brisket, as it gives it a lot of flavor.
To prepare the rub, in a bowl combine Brown Sugar (1 tablespoon), Paprika (2 teaspoon), Onion Powder (1 teaspoon), Garlic Powder (1 teaspoon), Dry Mustard (3/4 teaspoon), Ground Cumin (1/2 teaspoon), Salt (1 teaspoon), and Ground Black Pepper (1/2 teaspoon). Mix well.
Completely cover the brisket with the rub making sure to get the seasonings into every crevice of the meat. Cover and leave it to marinate in the fridge for a minimum of 2 hours up to 24 hours, the longer the better.
Once the meat has marinated, in the slow cooker begin to prepare the bbq sauce. Add into the slow cooker Garlic (2 clove), Apple Cider Vinegar (1/2 cup), Ketchup (1 1/2 cup), Brown Sugar (8 tablespoon), Onion Powder (2 teaspoon), Dry Mustard (2 teaspoon), Ground Black Pepper (2 teaspoon), Cayenne Pepper (1 teaspoon), and Worcestershire Sauce (1 tablespoon). Mix well until combined.
Place the marinated brisket into the slow cooker. You can spoon the sauce over the brisket, but it isn't necessary; the brisket only needs to be sitting in the sauce. You may cook either on high for 4 hours or cook on low for 8 hours. Because the meat is brisket and cooks better slowly, it is recommended to opt for the low setting, but the high setting is perfectly fine.
Remove the brisket. To thicken the sauce, either use the sear setting on your slow cooker to reduce it for a few minutes, or transfer to a sauce pan and reduce until it reaches the desired thickness.
Cut and portion the brisket, then serve topped with the BBQ Sauce. Enjoy!