Toss the cream cheese, mustard, dill, lemon and capers into a food processor and process them for a few seconds until they're smooth. If you don't have a food processor, soften the cream cheese for a few seconds in the microwave, then mix it with everything in a small bowl.

Spread the cream cheese mixture on two pieces of toasted try. Top each with a thick layer of smoked salmon, lettuce and red onion. Place one pile on top of the other then top the works with yet another slice of rye. Repeat with the remaining ingredients for the second sandwich. Cut in half - corner to corner-and pass them around.