Melt butter over medium heat in a large pot. Add leeks and stir to coat with butter. Cover the pot and lower heat, cook for about 10 minutes, until leeks soften.
Add garlic, potatoes, salt, and pepper. Cook for 1 minute then add the vegetable broth, water, thyme, and bay leaf. Bring to a boil then lower heat and cover pot, let simmer for 15 minutes, or until potatoes are tender.
Uncover and remove thyme and bay leaf. Use an immersion (or countertop) blender to blend the soup until smooth. Stir in green onions and hot sauce. Allow to cool for a couple minutes and serve. Enjoy!