Heat the olive oil in a soup pot over medium heat. Add the onion, celery, carrot, and salt and cook for 10 minutes, stirring often, until vegetables have started to soften.
Add the red pepper and oregano and cook another minute, stirring often to prevent burning.
Reduce heat to medium-low and add the broth and white beans. Simmer while you cook the tortellini.
I usually have leftovers so I cook the tortellini in a separate pot, then add the soup over the tortellini! If you want to cook the tortellini in the same pot, you can. To separate, bring a second separate pot of water to a boil and add the tortellini. Cook until tender according to package directions, and set aside. To cook together, add the tortellini to the soup. If you are doing this, add in an extra 2-3 cups of broth or water.
Add in the spinach and lemon juice and cook spinach until just wilted. Taste, adding more salt as desired, then serve.
If you made the tortellini separately, divide the tortellini into bowls and top with the soup. Or, divide the soup with the tortellini into bowls and top with parmesan cheese, if desired.
Notes
See above for how to serve the tortellini -- either in the soup or cooked separately. If you are planning leftovers, then I recommend serving them separately.To make this vegan, use a dairy-free tortellini like Kite Hill.