I have on occasion been served, and been disappointed with, sweet-and-sour-type brisket. If you see a recipe with grape jelly, run away.
More typical will be onions or onion soup mix (I prefer the former, which I sautee until a little brown before adding to the roasting pan); tomato paste, ketchup or chili sauce (again the first on the list is my preference); carrots, potatoes and/or parsnips (always the first, often the second, occasionally the third will find its way into my brisket); garlic; depending on how well your pan seals and whether you're using potatoes, liquids including red wine and water are often included (both). Note that many of those things are sweet (onions, carrots, all the tomato products), a few have sour notes (tomato items, wine), but the finished dish ends up far, far away from sweet-and-sour.
What is patriotism, but the love of good things we ate in our childhood?
-- Lin Yutang