How to Make It
In a large saucepan, heat the olive oil. Add the parsnips, sunchokes and garlic and cook over moderate heat, stirring, until lightly golden, 5 minutes. Stir in the garam masala, cumin, turmeric and 1 teaspoon of salt. Cook, stirring, until fragrant, 2 minutes. Add the water, chicken stock and cream. Bring to a simmer; cook until the vegetables are soft, 25 minutes.
Working in batches, puree the soup in a blender until very smooth. Pour the soup into a clean saucepan and stir in the lemon juice. Season with salt and pepper.
In a medium skillet, heat the olive oil. Add the walnuts and cook over moderately low heat, stirring, until golden, 3 minutes. Remove from the heat and stir in the garlic and lemon juice. Scrape the mixture into a small bowl and toss with the walnut oil. Cool to room temperature, then stir in the pear, parsley and tarragon; season with salt and pepper. Serve the soup sprinkled with the topping.