Set up grill for indirect cooking over medium heat (no direct heat source under brisket).
Rinse brisket with cold water and pat dry. Season with salt and pepper and place in foil baking pan. Sprinkle with meatloaf seasoning and pour over beer. Add enough apple cider to cover brisket halfway. Top with sliced onions and cover with heavy-duty aluminum foil.
Place pan on hot grill over a drip pan. Cover grill and cook 2 1/2 hours. If using charcoal, add 10 briquettes to each pile of coals every hour. Remove brisket from braising liquid and place directly on grill over the drip pan. Combine 2 cups of braising liquid with BBQ sauce. Mop brisket thoroughly with sauce. Add 1/2 cup of wood chips to each pile of coals. Cover grill. Turn and mop brisket every 20 minutes for 1 hour.
Transfer brisket to cutting board and let rest 10 minutes before slicing. Thinly slice against grain and serve with mop sauce on the side.
INDOOR: Preheat oven to 375 degrees F. Follow directions for preparing brisket. Cover pan with aluminum foil and bake in preheated oven for 2 1/2 to 3 hours. Remove brisket from braising liquid and place on foil lined baking sheet. Reduce oven temperature to 350 degrees F. Mop brisket with BBQ sauce return to oven. Turn and mop brisket with sauce 2 more times every 15 minutes. Remove from oven and let rest 10 minutes before slicing.