Begin by preparing your vegetables. Cut the potatoes into 1-inch cubes, zucchini into ½-inch slices, and carrots into ¼-inch rounds. Thinly slice the leek and chop the onion, while the celery should be cut into ¼-inch pieces.

Heat 2 tablespoons of frying oil in a large pot over medium heat. Add the chopped onion, sliced leek, and dried thyme. Sauté for about 8 minutes until the onions become translucent.

In the same pot, add another 2 tablespoons of oil and toss in the zucchini, potatoes, carrots, and celery. Allow the vegetables to cook undisturbed for about 3 minutes.

Return the sautéed onion, leek, and thyme mixture back to the pot. Pour in 8 cups of water and bring to a gentle simmer over low heat for about 15 minutes.

After simmering, add the green beans to the pot and bring it to a boil. Lower the heat again and let it simmer for an additional 8 minutes.

Introduce the green peas and canned cannellini beans into the soup. Cook together for 2 more minutes, then season with salt and pepper.

In a food processor, blend together the basil leaves, garlic, and grated Parmesan cheese until chunky. Slowly whisk in the olive oil.

Ladle the soup into bowls, leaving space for pasta. Cook the small elbow pasta separately and add it to each bowl right before serving. Stir in a heaped teaspoon of pistou into each bowl.