Rub brisket generously with salt and vegetable oil.
Heat a large saute pan over medium-high heat. Add vegetable oil to evenly coat pan and when the oil is hot and is just beginning to smoke, add the brisket and brown on both sides. Transfer the brisket to a shallow baking dish. Add the vegetables to the saute pan. Cook until they brown and start to soften, about 5 minutes. Then pour the vegetables over the brisket.
Whisk together the tomatoes, sugar, stock and vinegar in a mixing bowl then pour it into the same saute pan. Cook for a few minutes to get all the flavor out of the skillet, and then pour over the brisket. It should be at least 3/4 of the way submersed in the liquid. Cover the dish loosely with aluminum foil and bake for 8 to 10 hours until tender and the meat begins to fall apart. Slice thinly and serve with veggies and cooking liquid.