Mix together in a small bowl the cream cheese, creme fraiche, dill, lemon zest
and juice, and red onions
. Season with salt and pepper.
Spread a little of the cream cheese
mixture onto each of the pumpernickel
slices. Top half of the slices with two slices of smoked salmon, folded. Top with the remaining bread to make four sandwiches. Cut into thirds to make twelve mini sandwiches.