In a large soup pot, heat olive oil over medium high heat. Add the onion, celery, carrots, green beans, garlic, oregano, and red pepper flakes. Cook for 5 to 7 minutes or until the veggies begin to soften, stirring occasionally. Season with salt and pepper.
Add the vegetable broth and increase heat to bring to a boil, then slightly lower heat to a gentle boil. Allow the veggies to cook for 5 minutes.
Add the tortellini to the gently boiling soup and cook 5 to 7 minutes, or according to package instructions. Stir in the diced tomatoes and spinach leaves. Cook for another 3 to 5 minutes.
Serve warm! It tastes great with freshly grated parmesan cheese and crunchy bread.
Notes
You can store leftovers in a glass container in the fridge for up to 3 days. This soup would also freeze well. Leave a couple inches of headspace to allow the soup to expand while freezing.
Reheat the soup in a saucepan over medium-low heat or in the microwave until warmed through. If the tortellini absorb some of the liquid over time, add some water or broth when reheating.
To increase the protein content, add white beans or shredded chicken or turkey.