In a large, heavy-bottomed pot, add olive oil, onions, carrots, and celery. Set over medium heat and let sizzle for 4 to 5 minutes or until they begin to soften. Tie the bay leaves and rosemary together with kitchen twine and add them to the pot, followed by the tomatoes. Add boiling water to the pot, filling it just until all of the vegetables are submerged. Let it cook for another 10-15 minutes, and the minestrone is ready!