Mix Spread ingredients together.
Spread half on a flatbread in a square shape.
Top with half the smoked salmon.
Spread a flatbread with butter - just thinly, like buttering a piece of bread. Place the butter side down onto the salmon (Note 2)
Spread remaining Spread on flatbread, again in a square shape. Top with remaining salmon. Butter 3rd wrap and place butter side down onto the salmon.
Use a large flat object, like a cutting board, and press down lightly to smooth the surface and compress everything.
Cover with cling wrap and refrigerate for 4 hours (up to 48 hours) so the filling sets.
Using a serrated knife, trim edges to make a square. Don't cut down - filling may squirt out, cut back and forth in a sawing motion. Chef privileges: nibble on offcuts.
Cut square into 6 or 7 even strips, then each strip into squares. Serve with toothpicks, wedges of lemon and extra dill for garnish.
