Slice the leeks finely, about 1/8th of an inch.
Cut the potatoes into a 1-inch dice.
Heat the olive oil in a large soup pot over medium heat for 30 seconds.
Add the leeks and stir until to cover with the oil. Let cook for about 5 minutes, or until soft.
Add the potatoes and the vegetable broth, and bring to a boil.
Simmer for about 12-15 minutes, or until the potato pieces are fully cooked.
Turn off the heat (if using leafy greens, stir them in now), then let cool for 5 minutes.
Taste the soup and add salt and pepper as you desire.
Using an immersion (stick) blender, blend as much or as little of the soup as you like.
Serve hot and enjoy!