Take 1/4 cup of the broth and bring to a simmer in a stockpot. Add leek, salt, garlic and coriander. Sauté for a few minutes.
Add the next four ingredients with remaining broth (potatoes need to be covered with liquid). Bring to a boil then simmer, covered, until potatoes are soft and tender (about 10 minutes).
Remove bay leaf. Puree soup in a blender with miso, leaving some potatoes in the pot if you like the soup to be more chunky. It isn't necessary to put the whole amount of liquid into the blender. You can use a skimmer or slotted spoon to pull out the veggie bits and add in a cup or so of the soup broth then blend.
Return blended potatoes to pot and add in the spinach and herbs. Heat over a low flame. Season with salt and pepper to taste. Serve hot.

Potato and Leek Soup with Thyme & Spinach:
4-5 cup vegetable broth
2 large leek, white and light green parts, chopped
pinch of salt
1 tablespoon garlic powder or 2 cloves fresh garlic, minced
1 teaspoon coriander
3 potatoes, chunks (about 5 cups)
1 large bay leaf
1/2 cup unsweetened non-dairy milk
2 tablespoon nutritional yeast
handful fresh spinach
2 teaspoon fresh herb (like thyme)
1 tablespoon miso
white or black pepper and salt, to taste