Created by MsPia on November 28, 2014
Step 1: Spread the Dijon mustard over each of 4 slices of bread. Top each one with 1 slice of the Gruyere.
Step 2: Divide all of the smoked salmon and grated lemon zest among the 4 slices of bread. Season lightly pepper and cover with the remaining slices on Gruyere. Close the sandwiches.
Step 3: Butter the outsides of sandwiches; cook in a large skillet over medium/low heat until golden brown on both sides.