Susan's Brisket in the oven

Chopped bell pepper, onion and celery at HEB. One sweet onion sliced big. Rub the brisket with dry rub on both sides. Place in large roasting pan. Pour marinade on and marinade overnight in refrigerator.  Remove from refrigerator and cover with chopped veggies. I also pour a little balsamic vinegar over the brisket. It adds a little unique dimension of flavor and tenderizes as well.  Cover with foil tightly and bake at 350 degrees for 4 hours. Let it sit for about 30 min before slicing.