Combine mayonnaise and next 7 ingredients until well-blended. Stir in celery root. Cover and refrigerate at least 1 hour.
Combine olive oil and paprika; brush on scallops. Broil, sear, or grill scallops about 1 to 2 minutes per side or until heated through.
With a slotted spoon, divide celery root evenly among 8 plates, and top each with a scallop. Garnish, if desired. Serve immediately.
Chef John Recommends: A smooth, barrel-aged Sauvignon Blanc to complement the sweet scallops and creamy celery root salad. Alternative Pours: A Chardonnay or Pinot Blanc that has seen some wood. Or one of the "meritage" whites--handcrafted wines from Bordeaux grapes--being made in California, such as Caymus Conundrum.