Heat the olive oil in a large pot over medium heat. Add the onion, carrots and celery and cook 5-6 minutes, stirring occasionally, until softened.
Add the garlic and oregano and cook 1 minute, until fragrant.
Add the diced tomatoes with their juices, the vegetable broth and the beans. Bring to a boil, then lower the heat and simmer 5 minutes.
Stir in the pasta and simmer 10-12 minutes, until the pasta is al dente.
Stir in the spinach and cook 2 minutes, until wilted. Season with salt and black pepper to taste, then serve hot.