Soak the hickory chips in water for 1 hour before grilling.
For the brine: Combine the apple cider and water in a large, oval Dutch oven. Add the salt and sugar and stir until it dissolves. Add the black peppercorns and bay leaves. Add the brisket and let soak in the brine solution for up to 3 hours in the refrigerator.
For the rub: Combine the salt, paprika, pepper, sugar, and onion powder together in a bowl.
For the sauce: Add all the ingredients to a saucepan and simmer for 5 minutes so the butter can melt and the flavors can marry.
For the brisket: Set up your smoker with charcoal and hickory chips using indirect heat. Heat the grill to 275 degrees F.
Remove the brisket from the fridge. Drain from the brine and pat dry with paper towels. Place on a rimmed sheet tray. Rub the brisket with the spice mixture.
Place the seasoned brisket fat cap side up on the grill and smoke for 2 hours with the grill lid covered. (Starting with the fat cap side up allows the fat to melt into the brisket, adding moisture and flavor.) Flip and smoke 2 more hours. Check and refill charcoal levels and hickory chips throughout the smoking process, keeping the temperature at a constant 275 degrees F.
Remove the brisket from the grill and wrap in a double layer of heavy-duty aluminum foil. Place back on the grill for 1 1/2 more hours.
Remove the brisket from the grill, unwrap the foil, brush the brisket with sauce (or serve on the side), tent with foil, and let rest for 30 minutes before slicing across the grain. Drizzle more sauce when serving.
Brining the brisket before smoking adds flavor and tenderness to the brisket. The brisket will be tender at 200 degrees F. But you can also do the fork test - stick a fork in the side of the flat and twist. If it turns easily, it is ready. Brisket, being a Texas specialty, is wrapped in foil the last hour or 2 of smoking to ensure that the meat is tender and juicy. This is called the "Texas Crutch". Essentially, the brisket steams until it becomes tender. Brisket is much less forgiving than pork shoulder, which is a Memphis specialty, so the foil adds ease for the casual weekend barbecue king. The foil also can save charcoal costs and attentive cooking time. You can wrap the brisket in foil and finish in an oven heated to 275 degrees F for the remainder of the cooking time. Always slice a brisket across the grain. Leftover brisket can dry out the day after you cook it. Chopping the leftovers and mixing with BBQ sauce for a brisket sandwich is a great way to make use of them.