Peel and dice the potatoes, celery, carrot, onion, broccoli stalk, and fennel. In a large pot, heat some olive oil and sauté the vegetables over medium heat until softened, about 10 minutes.

Stir in finely chopped parsley and a touch of lemon zest, mixing well to enhance the flavor base.

Make a small space in the center of the pot, add minced garlic and finely chopped basil, and sauté until fragrant, about 2-3 minutes. Stir to combine with the vegetable base.

Clear another space in the pot, add a little olive oil, and stir in the tomato paste. Repeat with diced tomatoes. Season with salt and pepper, then mix everything together.

Pour in 5 cups of water (or broth) and bring the soup to a boil. Increase the heat to high for a full boil, then lower to a simmer. Stir in the fregola sarda and cook until the pasta is tender. Add the beans (softened if canned, or soaked overnight if dried) near the end.

Remove from heat and adjust the seasoning with a splash of red wine vinegar.

Note: If using dried beans soaked overnight, add them at the beginning with the vegetables to ensure they cook through.

Using a mortar and pestle, combine chopped basil, a pinch of salt, and olive oil into a  paste. Drizzle this over each serving of soup for an aromatic finishing touch.