Place brisket in a large Dutch oven or heavy pot. Add cabbage, crushed tomatoes, tomato sauce, sugar, vinegar, salt, and onion powder and cover. Bring to a boil. Reduce to a simmer and cook about 3 hours or until meat is very tender.2. Meanwhile, prepare the potatoes. Preheat oven to 400°F. On a large baking sheet, toss potatoes with oil, garlic, thyme, salt and pepper. Roast 30 to 40 minutes or until tender. Serve slices of brisket with roasted potatoes and a little extra sauce.