Sauté beef and salt on high heat in a large nonstick skillet until browned, breaking up meat into small bits as it cooks. Add the onion, celery, and carrots and sauté 3-4 minutes.
Transfer to the slow cooker along with the tomatoes, stock, and bay leaf. Cover and cook on low 8 hours.
Just before it’s ready, add the pasta to the slow cooker and cook according to package directions.