Preheat the oven to 375 degrees.For the Mushrooms:

In a 10- to 12-inch cast-iron skillet over medium heat, add the mushrooms and cook until any moisture from the mushrooms releases and evaporates. Add 1 tablespoon each of the butter and olive oil, and the shallot and cook until the mushrooms start to crisp up and turn golden. Sprinkle with the thyme, 1/2 teaspoon of the salt, and 1/4 teaspoon of the pepper. Transfer to a plate. In the same skillet, heat the remaining 1 tablespoon each butter and olive oil over medium-low heat. Add the onion and sauté for 30 minutes, stirring gently every 4 to 5 minutes. Turn the heat down to low if the onions are cooking too quickly. Once caramelized, sprinkle with the remaining salt and pepper. Return the mushrooms to the skillet, stir, and set aside.For the Rub: To make the rub, stir together the Baharat, brown sugar, salt, and pepper in a small bowl. Generously rub the steaks on both sides.For the Steaks: To prepare the steaks, in a 10- to 12-inch cast-iron skillet, heat the olive oil over medium-high heat. Add the steaks and cook for 3 minutes on each side, or until a nice golden crust forms. Transfer the steaks in the pan to the oven. Continue cooking for 6 minutes for medium-rare. Remove from the oven, loosely cover with foil, and allow the steaks to rest for at least 5 minutes. Reheat the skillet with the mushrooms for several minutes, or until nice and hot. Slice the steaks into ½-inch-thick slices and serve half of a rib-eye to each guest with the mushroom mixture on the side.