Toast the Foundation: Preheat your oven's broiler to high. Arrange the 20 whole-grain baguette slices in a single layer on a baking sheet. Broil for 1-2 minutes per side, watching carefully, until they are golden brown and crisp. Remove from the oven and set aside to cool completely.
Prepare the Salmon: Place the smoked salmon slices in a fine-mesh sieve. Gently rinse under cold running water for 10-15 seconds. Carefully pat the slices completely dry with paper towels. Cut the salmon into 20 bite-sized pieces.
Create the Avocado Schmear: Scoop the flesh of the two avocados into a medium bowl. Add the fresh lemon juice and mash with a fork to your desired consistency, leaving some small chunks for texture.
Infuse the Flavor: Fold the chopped fresh dill, lemon zest, and freshly cracked black pepper into the mashed avocado. Stir until just combined; do not overmix.
Assemble the Crostini: Spread a layer of the herbed avocado mixture evenly over each toasted baguette slice, covering it from edge to edge.
Adorn and Finish: Top each avocado-covered crostini with one piece of the prepared smoked salmon. If using, sprinkle a few rinsed capers over the toasts. Arrange the finished crostini on a serving platter. Just before serving, drizzle the extra virgin olive oil evenly over all the crostini and garnish with fresh dill sprigs.