Just before serving, gently combine the shrimp, and crabmeat with the zest, juice, mayonnaise, mustard and chopped asparagus stems; add seasoned salt to taste.
To serve: spread some seasoned salt on a plate, rim the martini glasses with lemon juice and dip them into the salt. Line each glass with a chard leaf and fill with the crab mixture. Garnish each martini with 3 asparagus spears, an olive and a lemon slice. Serve with water crackers or toast points.
Cook's note: Don't put this together until the last minute.