PreparationMake mousse: Sprinkle gelatin over water in a 1-quart heavy saucepan and let soften 1 minute. Cook mixture over low heat, stirring, until gelatin is dissolved. Add 1/4 cup sour cream and cook over low heat, whisking constantly to prevent clumping, 3 minutes. Transfer to a bowl and stir in salmon, horseradish, dill, salt, pepper, and remaining 1/2 cup sour cream. Chill, covered, until firm, about 1 hour. Make pizzelle while mousse chills: Whisk eggs in a bowl until frothy, then whisk in butter, flour, water, dill, salt, and pepper until smooth. Heat pizzella iron until hot, then brush with melted butter. Spoon 1 tablespoon batter in center of each grid and cook until underside is golden, 2 to 4 minutes. Transfer each pizzella to a cutting board and quarter while hot. Transfer to a rack to cool completely. Make more pizzelle in same manner. Top each pizzella quarter with 1/2 teaspoon salmon mousse. *Available at Sweet Celebrations (800-328-6722). Cooks' note:Pizzelle (without topping) can be made 1 day ahead and kept in an airtight container at room temperature.
PreparationMake mousse: Sprinkle gelatin over water in a 1-quart heavy saucepan and let soften 1 minute. Cook mixture over low heat, stirring, until gelatin is dissolved. Add 1/4 cup sour cream and cook over low heat, whisking constantly to prevent clumping, 3 minutes. Transfer to a bowl and stir in salmon, horseradish, dill, salt, pepper, and remaining 1/2 cup sour cream. Chill, covered, until firm, about 1 hour. Make pizzelle while mousse chills: Whisk eggs in a bowl until frothy, then whisk in butter, flour, water, dill, salt, and pepper until smooth. Heat pizzella iron until hot, then brush with melted butter. Spoon 1 tablespoon batter in center of each grid and cook until underside is golden, 2 to 4 minutes. Transfer each pizzella to a cutting board and quarter while hot. Transfer to a rack to cool completely. Make more pizzelle in same manner. Top each pizzella quarter with 1/2 teaspoon salmon mousse. *Available at Sweet Celebrations (800-328-6722). Cooks' note:Pizzelle (without topping) can be made 1 day ahead and kept in an airtight container at room temperature.