How to Make It
Preheat the broiler and position a rack 6 inches from the heat. In a bowl, beat the butter with the Dijon and grainy mustards, lemon zest and 1 tablespoon of the dill and season with salt and pepper.
Spread the baguette slices on a large rimmed baking sheet and broil until golden and crisp, 1 1/2 minutes per side. Let cool.
Spread the toasts with the mustard butter, top with the smoked salmon and arrange on a platter. Sprinkle with the remaining 1 tablespoon of dill and serve.