Adapted from Fagioli by Judith Barrett, this vegetable-laden soup became a staff favorite when we made it in the Rancho Gordo test kitchen. It's based on a soup served in Umbria when asparagus are plentiful at the market. A thick slice of toasted bread smeared with butter is the perfect accompaniment.

• 5 tablespoons olive oil (divided use), plus more for serving
• ½ cup chopped shallots or red onion
• 1 celery stalk, finely chopped
• 1 garlic clove, minced
• 1 medium Yukon Gold (or other waxy) potato, peeled and chopped
• ½ cup tomato puree
• 1 pound fresh asparagus, bottom 2 inches cut off and discarded, stalks peeled and roughly chopped
• 2 cups cooked Rancho Gordo white heirloom beans, such as Marcella or Alubia Blanca, cooking liquid reserved
• Vegetable or chicken broth, as needed
• 2 ounces prosciutto, diced (optional)
• Salt and pepper
• Chopped fresh parsley for garnish (optional)

1. In a soup pot over medium heat, warm 4 tablespoons of the olive oil. Add the shallots, celery, and garlic, and cook, stirring, about 5 minutes, until the vegetables begin to soften. Add the potato, tomato puree, asparagus, and beans. Stir in 4 cups of the reserved bean-cooking liquid and/or broth and simmer, stirring occasionally, until the asparagus and potatoes are tender, about 30 minutes.
2. Meanwhile, if using prosciutto, warm the remaining 1 tablespoon olive oil in a small skillet over medium heat. Add the prosciutto and fry until golden and crisp, 5 to 7 minutes. Remove from the heat and set aside.
3. Transfer the soup to a blender or food processor or use an immersion blender, and process until smooth. Return to the pot, season with salt and pepper, and reheat before serving. Divide among bowls, and top with fried prosciutto and parsley, if using.