They've sold more than two million books. Now Janet and Greta Podleski share a favourite recipe from "The Looneyspoons" collection.

Roasted Sweet Potato Soup with Orange and Ginger (Makes 6 servings)

Ingredients:

• 6 cups peeled and cubed sweet potatoes (about 3 large)
• 1 1/2 cups coarsely chopped onions
• 1 Tbsp olive oil
• 1 tsp minced garlic
• 5 cups reduced-sodium vegetable or chicken broth
• 1 Tbsp each grated orange zest and ginger root
• 1 whole clove
• 1/2 tsp each ground cumin and salt
• 1/4 tsp freshly ground black pepper
• 6 Tbsp light (5 per cent) sour cream
• Minced fresh cilantro for garnish (optional)

Directions:

Spray a shallow roasting pan with cooking spray. Add yams or sweet potatoes, onions, olive oil and garlic. Stir well. Roast, uncovered, at 425 ºF (218 ºC) for 25 minutes. Stir once, halfway through cooking time.

Transfer mixture to a soup pot. Add broth, orange zest, ginger root, clove, cumin, salt and pepper. Bring to a boil. Reduce heat to medium-low and simmer, covered, for 10 minutes.

Working in batches, carefully transfer the soup to a blender or food processor and purée until smooth. Serve hot with a swirl of sour cream in the center. Garnish with fresh cilantro, if desired.

Recipe tip: Add 1 tsp medium curry powder to step two for even more zip!

Per serving: 209 calories, 3.7 g total fat, (0.2 g saturated fat), 6 g protein, 39 g carbohydrate, 4.9 g fiber, 1 mg cholesterol, 292 mg sodium.