Place the potatoes and water in a large pot. Add the bay leaf, sage, thyme, miso, and cilantro and bring to a boil. Reduce heat to medium-low. Cover and simmer until the potatoes have softened, about 30 minutes.
Remove the potatoes from the pot and puree in a food processor until smooth or, place potatoes in a bowl and mash with a potato masher or a hand blender until smooth.
Return the potatoes to pot. Stir in the non-dairy milk and ground pepper. Simmer for another 8 minutes and serve.