Layered Shrimp and Crab Cocktail

Vinaigrette 3/4 cup olive oilGrated zest of 1 lemon 1/4 cup fresh lemon juice1 teaspoon Dijon mustard1 clove garlic, finely chopped2 teaspoons chopped fresh oreganoPinch of saffron threadsKosher salt and freshly ground pepperSeafood cocktail1 pound peeled cooked shrimp (prawns)3 celery stalks, thinly sliced3 green onions, including tender green tops, chopped1 pound crabmeat, picked over for shell fragments1 fennel bulb, trimmed, quartered lengthwise, cored and sliced crosswise paper-thin6 thin lemon slices6 small bay leavesFor the vinaigrette: In a small bowl, whisk together the olive oil, lemon zest, lemon juice, mustard, garlic, oregano and saffron. Season to taste with salt and pepper.For the seafood cocktail: Wash and thoroughly dry six 1 1/2-cup canning jars with glass lids and wire bale closures. Place half of the shrimp in the bottoms of the 6 jars, dividing them evenly. Top with half of the celery, green onions, crabmeat and fennel slices. Repeat the layers, starting with the shrimp and finishing with the fennel slices. Drizzle the vinaigrette into the jars, dividing it evenly. Garnish the top of each jar with a lemon slice and a bay leaf. Close the lids and refrigerate the jars for 2 hours or up to 12 hours to blend the flavors.Just before serving, rock each jar back and forth a few times to distribute the vinaigrette. Serve cold directly from the jars.Serves six.Cook's notes: Use ice packs for transport and keep the cocktails cold until ready to serve. Look for ready-to-serve shrimp and crabmeat at seafood counters.Nutrition values per serving: 383 calories, 29 g fat (4 g saturated), 5 g carbohydrates, 2 g fiber, 26 g protein, 157 mg cholesterol, 608 mg sodium."Williams-Sonoma Outdoor Entertaining" (2006 Weldon Owens Inc., $24.95)