Heat the olive oil in a large pot over medium heat.
Add the chopped onion, carrots, and celery and sauté until softened.
Stir in the minced garlic and cook for an additional minute.
Add the diced zucchini, green beans, and asparagus.
Pour in the diced tomatoes with their juices and add the vegetable broth.
Add the cannellini beans, oregano, salt, and pepper.
Bring the soup to a gentle boil, then reduce heat to low and simmer for about 20 minutes.
Fold in the spinach or kale and cook for an additional 5 minutes.
Finished with lemon juice and zest before serving.