Stewed white beans in tomato sauce are a staple vegetarian side across Italy. This mediterranean dish is high in protein and fiber, a fresh, healthy family accompaniment for any main course.
Heat the olive oil in a heavy-bottomed skillet or Dutch oven over medium heat until shimmering, but not smoking.
Add the chopped onion, celery, and carrot; sauté on medium-low heat for 8 minutes, stirring often, until the vegetables are softened and aromatic.
Stir in the minced garlic and dried oregano; cook for 1 minute, taking care not to let the garlic burn.
Pour in the diced tomatoes with their juices; season lightly with salt and pepper. Let simmer on medium-low heat for 10 minutes, until the sauce begins to thicken and the vegetables are tender.
Add the cannellini beans. Stir gently to coat in the sauce. Partially cover and simmer on low heat for 15–20 minutes, stirring occasionally to keep the beans from sticking, until the flavors meld and sauce is richly flavored.
Taste and adjust for salt and pepper. Just before serving, sprinkle with chopped fresh parsley for freshness.