Step 1Place the onions, potatoes, garlic, water, salt and pepper into a large soup pot.
Step 2Bring to a boil, then cover and simmer slowly until the potatoes are tender, about 20 minutes.
Step 3Add the spinach to the pot and simmer for an additional minute.
Step 4Use a blender or food processor to puree the soup mixture, in batches, adding the dill and basil in the last batch. (Or you can keep the mixture in the soup pot and use an immersion blender to puree.)
Step 5Heat the blended soup mixture in the pot. Serve hot.