Heat all ingredients to boiling in Dutch oven or stockpot; reduce heat. Cover and simmer about 1 hour, stirring occasionally. Cool slightly. Strain and refrigerate. Stir before measuring. About 8 cups stock.
NOTE: Use strong vegetables, such as broccoli, cabbage, cauliflower, turnips, and rutabagas sparingly combined with mild vegetables.
Heat 1 tbsp. olive oil in stock pot and add first nine ingredients. Add 1 tbsp. kosher salt. Let cook about 2 minutes. Add tomatoes. Heat through then add vegetable stock. Bring to a boil and let simmer about 45 minutes (longer if you like your veggies less crisp). Just before serving, add the spinach and heat through. Adjust salt and pepper to taste. Use any vegetables you like, these are just a guide. Leave out what you don't like.