Heat some cooking fat in a large saucepan placed over medium heat.
Cooking fat
Add the onions and garlic and cook until soft and fragrant, about 6 minutes.
2 large yellow onions, 4 large cloves garlic
Add the carrots and bell peppers and cook for another 6 minutes.
1 cup carrots, 1 green bell pepper
Add the chile powder, oregano, cumin, and cayenne. Season to taste with salt and pepper and cook for 1 to 2 minutes.
3 tbsp. ancho chile powder, 1 tbsp. dried oregano, 1 tbsp. ground cumin, ¼ tsp. cayenne pepper, Sea salt and freshly ground black pepper
Stir in the tomatoes and the tomato paste.
6 oz. tomato paste, 28 oz. can diced tomatoes
Add the brisket cubes and bring them to a boil.
1 lb. leftover brisket
Reduce the heat to low. Simmer, covered, until the brisket is tender and the sauce is flavorful about 30 minutes.
Season again to taste with salt and pepper, and add the vinegar.
Dash balsamic vinegar
Serve warm.