Blanch the almonds in boiling water for 30 seconds. Drain, and plunge almonds into cold water. Drain, and squeeze the almonds between your fingertips to remove the skins. Compost or discard the skins. Put the blanched almonds and 1 cup of the vegetable stock in a blender, and blend until smooth, about 1 minute. In a large pot, combine the potatoes, leeks, and the remaining 4 cups vegetable stock and bring to a simmer over medium heat. Cover and boil until the potatoes are tender, about 10 to 15 minutes. Stir the blanched almond mixture, parsely, lemon juice, salt, and pepper into the soup. Bring to a simmer and cook, stirring often, until thickened, about 2 minutes. Transfer the soup to a food processor and process, in batches if necessary, until smooth. Serve immediately.