In a large saucepan, bring 2 cups water, the rice and 1/2 teaspoon salt to a boil. Cover the pan, lower the heat and simmer until tender, about 40 minutes. Remove from the heat and let stand, covered, for 10 minutes; fluff with a fork. Meanwhile, heat a large skillet over medium heat. Add 1 tablespoon extra-virgin olive oil and the sausage and cook, breaking up the meat, until browned, about 5 minutes. Using a slotted spoon, transfer the sausage to the rice. Return the skillet to the heat and add 1 more tablespoon olive oil, the bell peppers, mushrooms and onion. Season with salt and pepper and cook until the vegetables are crisp-tender, about 5 minutes. Add the veggies to the sausage and rice and toss.