Heat vegetable stock over low heat in a large soup pot.
Heat oven to 400°F. Spread coriander and cumin seeds on an unlined pan, and bake for 1 minute, or until fragrant. Remove immediately, and crush in a mortar and pestle, or on a cutting board with a rolling pin. (You may wish to toast the additional ½ teaspoon cumin seeds required for the spiced yogurt now as well.)
Heat oil in a large soup pot, and add onions, ¼ teaspoon salt, and a pinch of pepper. Cook over medium heat until onions are soft, about 5 minutes. Add garlic and ginger, and cook 1 minute more. Add wine and cook until the pan is nearly dry, about 3 minutes. Stir in toasted ground coriander and cumin, followed by carrots, parsnip, potato, ¼ teaspoon salt, and a pinch of pepper.
Add 5 cups of stock, and simmer uncovered, until vegetables are tender, 35 to 40 minutes.