Creamy parsnip soup and spicy roasted parsnip soup are delicious variations. To make spicy parsnip soup, preheat the oven to 425 degrees Fahrenheit. Whisk together 2 tablespoons olive oil, 1 teaspoon coriander seeds, 1 teaspoon cumin seeds, 1/2 teaspoon ground turmeric and 1/2 teaspoon mustard seeds. Toss in 1 chopped onion, 2 garlic cloves, 2 quartered plum tomatoes and approximately 1 1/2 pounds diced parsnips. Spread the vegetables on a baking sheet, and roast for 30 minutes.
Afterwards, puree the vegetables and 2 1/2 cups stock in a food processor. Add to a pot, and stir in 2 1/2 cups vegetable stock. Bring the soup to a simmer, remove from the heat, and squeeze in a tablespoon of fresh lemon juice. Serve hot.
For creamy parsnip soup, heat 2 tablespoons butter in a stockpot over medium heat. Stir in 1 1/2 sliced leeks. Cook for five minutes. Add 1 pound chopped parsnips, 2 chopped apples, 1 cubed potato, 14 1/2 ounces chicken stock and 4 cups water to the pot. Bring to a boil, and then reduce the heat. Simmer the soup for 25 minutes.
Use a blender or a food processor to puree the soup in batches. Return the puree to the pot. Stir in 1/2 cup heavy cream. Season the soup with salt and pepper.