Hammer each one of the steaks on both sides. Mix the cumin, half of the salt, and the pepper together. Season the steaks. Reserve for about 30 minutes.
In a large pan, sauté the onion and the bell peppers in 2 tablespoons of oil over medium-high heat. Then, add the garlic and sauté for about 30 seconds. Add the tomatoes and let sauté for 2 minutes, stirring occasionally. Reserve.
In a separate large heavy-bottom pan, brown the steaks in 2 tablespoons of oil over medium-high heat. Add the vinegar and let evaporate a little bit. Add the stock, the tomato paste, and the other half of the salt. Stir. Add all the vegetables and press a little bit with a smasher.
Reduce the heat to low and cover the pan. Let cook for about 1 hour or so, stirring occasionally.
Serve with mashed potatoes or with a hard-crust bread, or -- the way that we use to eat it at my mother's house: with white rice, beans, and potato cakes (the recipe for which will be posted soon).