Ingredients

• 1 cup chicken stock or reduced-sodium chicken broth
• 1 1/2 cups thinly sliced celery (about 3 ribs)
• 1/2 cup chopped peeled potato
• 1/4 cup finely chopped onion
• 1/2 cup flat-leaf parsley sprigs
• 1 lb bay scallops (preferably Nantucket Bay), tough ligament removed from side of each if attached
• 1 Tbsp vegetable oil
• 3 Tbsp black truffle butter, softened
• Garnish: chopped celery leaves

Instructions

1. Simmer broth, celery, potato, onion, and 1/4 tsp salt in a small heavy saucepan, covered, stirring occasionally, until vegetables are tender, about 15 minutes. Add parsley and cook, uncovered, 1 minute. Purée mixture in a blender until very smooth (use caution when blending hot liquids). Keep warm in saucepan.
2. Pat scallops dry and season with 1/4 tsp salt and 1/8 tsp pepper. Heat oil in a 12-inch heavy nonstick skillet over medium-high heat until it shimmers, then sauté scallops until barley cooked through, 2 to 3 minutes. Add truffle butter and stir until melted, then transfer scallops with a slotted spoon to a bowl. Stir celery purée into truffle butter in skillet. Spoon onto plates, then mound scallops in center and sprinkle with celery leaves.
3. Purée (without truffle butter) can be made 1 day ahead and chilled. Reheat in a microwave or in a saucepan over low heat before stirring into truffle butter.