Preheat your oven to 325 degrees.
Season brisket on both sides. Combine chili sauce, brown sugar, and beer. Slice your onions and lay them on the bottom of your roasting pan. Put the brisket on the onions (fat side up). Lay additional onions on the top (if you like lots of onions!).
Bake uncovered for 1.5 hours. Bake another 1.5 hours covered. Try to baste it in-between about two times. Total baking time should be 3 hours, or until it’s fork-tender.
Can be sliced at the table or let it cool a little and slice, then put it back in the roasting pan to reheat with the gravy.
