Prepare the Sofritto: Heat olive oil in a large pan over low heat. Add the chopped onion or leek and cook gently until translucent, around 5 minutes. Do not let it brown.

Add the Cauliflower and Potato: Toss the cauliflower florets and diced potato into the soffritto, and stir for a minute to coat with the oil.

Add the Liquid: Pour in enough broth (or water) to cover the vegetables. Bring to a gentle simmer and cook for about 15-30 minutes until the cauliflower and potato are tender.

Blend: Once the vegetables are soft, use an immersion blender or a countertop blender to puree the soup until smooth and velvety. If using a countertop blender, do so in batches and make sure to vent the lid to release steam.

Adjust the Texture: If the soup is too thin, simmer uncovered to reduce it. If it’s too thick, add a little more broth or water to reach the desired consistency.

Finish the Soup: Taste and adjust seasoning with salt and pepper. Optionally, stir in an egg yolk for added richness. If you want a creamier soup, add a splash of cream at the end and gently warm.

Serve: Ladle the soup into bowls and drizzle with extra virgin olive oil. Garnish with chopped parsley, chives, croutons, or a sprinkle of grated Parmesan or Pecorino Romano.

Optional Topping: If desired, crisp up some guanciale in a pan and sprinkle on top of the soup.