For the steaks: In a shallow baking dish, combine the steaks with the olive oil, rosemary pieces, and salt. Let them marinate while you prepare the mushrooms. For the mushrooms: In a large skillet, heat the olive oil over medium heat. Add the shallots, and cook until the begin to soften, about 4 minutes. Add the mushrooms, and cook until they release their liquid and soften, about 8 to 10 minutes. Increase the heat to high, and reduce away any excess liquid. Once the skillet is dry, make a space in the pan and drop in the tomato paste. Let it toast in this hot spot for a minute or two, then stir it into the mushrooms. Add the rosemary, and season the mushrooms with the salt. Add the Marsala and white wine, and simmer until the mushrooms are tender and glazed with the cooking juices, about 10 to 12 minutes. Remove the rosemary. While the mushrooms simmer, cook the steaks. Heat another large skillet over high heat. When the skillet is very hot, remove the steaks from the marinade, picking off any rosemary pieces, and add them to the skillet. Sear until they are well browned on both sides, about 3 to 4 minutes per side for medium rare. Let them rest on a cutting board for 5 minutes. Divide the mushrooms among four serving plates. Top each serving with a piece of steak, and serve immediately. Or set the steaks on hot plates and top with hot mushroom sauce.