Ingredients

• 8 cups water
• 1 1/2 teaspoons white wine vinegar
• 2 pounds Jerusalem artichokes (also called sunchokes)*
• 3 tablespoons butter
• 1 cup chopped onion
• 1 cup chopped leek (white and pale green parts only)
• 2 garlic cloves, chopped
• 7 cups (or more) vegetable broth
• 1/2 cup heavy whipping cream
• Ground white pepper
• Shelled pumpkin seeds, toasted
• Pumpkin seed oil (optional)
• Sautéed chanterelle mushrooms (optional garnish)

Instructions

1. Mix 8 cups water and vinegar in large bowl. Working with 1 Jerusalem artichoke at a time, peel and place in vinegar water to prevent discoloration. Set aside.
2. Melt butter in heavy large pot over medium heat. Add onion, leek, and garlic; sprinkle with salt and sauté until soft and translucent, stirring often, about 12 minutes. Drain artichokes; rinse well and drain again. Cut into 1-inch pieces. Add to onion mixture and sauté 5 minutes. Add 7 cups vegetable broth, increase heat to high, and bring to boil. Reduce heat to medium-low, cover, and simmer until artichokes are very tender, about 1 hour. Cool slightly.
3. Working in batches, puree soup in blender until very smooth. Return to pot. Rewarm soup, adding more broth by 1/4 cupfuls if needed to thin. Stir in cream and season to taste with salt and white pepper. do ahead Can be made 1 day ahead. Cool, cover, and chill. Rewarm before continuing. Divide soup among bowls and garnish with toasted pumpkin seeds; top with a drizzle of pumpkin seed oil and some sautéed mushrooms, if desired.
4. Tubers of a variety of sunflower; available in the produce section of some supermarkets and at farmers' markets.