Carefully pour the tomato liquid from the can into a large soup pot. Take the tomatoes out one by one and gently squeeze them out into the pan. Pull the whole tomatoes apart into bite-sized pieces and add to the pot. Add the broth, onion flakes, garlic powder, Italian seasoning, bay leaf, vinegar, carrots, red pepper flakes, celery seed and curry. Cover and bring to a boil.
Once boiling, reduce to low and simmer for 25 minutes. Meanwhile, cook the squash. Taste the soup, if it is too acidic add sugar as needed 1 tbsp at a time. Stir and cook for 5 more minutes. Remove the bay leaf and add salt and pepper to taste. Ladle soup into a bowl, filling just slightly more than half way. Add cooked spaghetti squash (use a fork to gently pull the flesh off in strands) and serve with vegan Parmesan if desired. Store leftovers separately with the squash in one container, soup in another.