- In a large pot, heat the olive oil over medium heat. Add the leeks and sauté until soft, about 4 minutes. Add the garlic and sauté for another minute.
- Add the potatoes, rosemary, thyme, sage, broth, and water. Bring to a boil, then reduce the heat and simmer until the potatoes are tender, about 15 minutes. Turn off the heat.
- Add the nutritional yeast, lemon juice, and liquid smoke. Use an immersion blender to blend the soup until smooth (or mostly smooth with a few potato chunks—your call).
- Alternatively, you can transfer the soup in batches to a blender and carefully blend until smooth.
- Add salt and pepper. Serve topped with bacon crumbles and green onions, if desired. Leftovers will keep in an airtight container in the fridge for 5 to 6 days.