Trim and thinly slice the Leeks (white and light green parts), then rinse them thoroughly under cold water to remove any grit and drain.
Peel and cut the Potatoes into roughly 1-inch cubes; peel and slice the Carrots into rounds; and finely dice the Onion.
Mince the Garlic finely so it will melt into the soup as it cooks.
Heat a generous splash of Extra-virgin olive oil in a large pot over medium heat. Add the onion and garlic and sauté until the onion is translucent and fragrant, about 4–5 minutes.
Add the sliced leeks and carrots to the pot and cook, stirring occasionally, for another 5 minutes until the leeks begin to soften.
Stir in the diced potatoes, then pour in enough Water to cover the vegetables by about an inch. Toss in the Bay leaf and bring the mixture to a gentle simmer.
Reduce the heat and simmer until the potatoes and carrots are tender, about 20–25 minutes. Remove and discard the bay leaf.
For a smoother texture, partially purée the soup with an immersion blender or mash some of the potatoes against the side of the pot; leave it chunkier if you prefer.
Season to taste with Salt, give the soup a final drizzle of extra-virgin olive oil if desired, and serve hot.
