How can this gnarled and knobby vegetable offer such elegance? This soup deserves a pedestal, as the creamy alabaster liquid flecked with bits of brown, elicits looks of surprise from guests followed by sounds of happy pleasures.
A blender or a food processor; 8 warmed, shallow soup bowls.
2 quarts (2 l) whole milk
2 teaspoons fine sea salt
2 pounds (1 kg) Jerusalem artichokes (sunchokes), scrubbed but not peeled
1/4 cup (30 g) salted pistachios, toasted (optional)
Best-quality pistacho oil, such as Leblanc brand, for garnish (optional)
1. Rinse a large saucepan with water, leaving a bit of water in the pan (this will prevent the milk from scorching and sticking to the pan.) Pour the milk into the pan and add the salt.
2. Trim the Jerusalem artichokes, and chop them coarsely, dropping them into the milk as you work (this will prevent the vegetable from turning brown as it is exposed to the air). When all the Jerusalem artichokes are prepared, place the pan over medium heat and cook gently until they are soft, 35 to 40 minutes. Watch carefully so the milk does not boil over. The milk may curdle, but that will not alter the texture or flavor of the final soup.
3. Transfer the mixture, in small batches, to the blender or food processor. Do not place the plunger in the feed tube of the food processor or in the lid of blender, or the heat will create a vacuum and the liquid will splatter. Puree until the mixture is perfectly smooth and silken, 1 to 2 minutes.
4. Return the soup to the saucepan and reheat gently. Taste for seasoning. Transfer it to the warmed, shallow soup bowls, garnished, if desired, with pistachios and pistachio oil and serve.