Assiette Champenoise feels inseparable from Champagne country, not because it leans on the obvious symbols, but because Arnaud Lallement's cooking shares the region's love of clarity, tension and finesse. The restaurant outside Reims is polished and serene, yet the plates can be boldly flavored, especially when seafood, shellfish, poultry and bright sauces meet the snap of great wine. It is a luxurious meal, but one with a clean line through it, like bubbles rising through something richer than they first appear.