Cut squash in half length wise and scoop out seeds. Lay skin side up in a 13×9 Pyrex dish and pour ½ inch of water in the bottom of the pan. Bake at 400 degrees for 30-40 minutes, until flesh is very tender. Once done, scoop out flesh with a fork so it breaks apart into strings, set aside. Please note that you can also microwave the squash, upside down for approx. 10 minutes or until you can stick a fork through the skin.
In a small bowl, whisk together the next 5 ingredients.
Heat olive oil in a large skillet over medium high heat. Add onion and celery, and cook, stirring often, until tender, about 3-4 minutes. Stir in cabbage until heated through, about 1 minute.
Stir in spaghetti squash and sauce mixture until well combined, about 2 minutes.
