If utilizing canned salmon, drain it aggressively through a fine-mesh colander. Meticulously remove and discard all skin and bones from the fish. Flake the meat thoroughly with a fork and set aside.

Place the fully softened cream cheese, buttermilk, chopped green onions, fresh lemon juice, Worcestershire sauce, minced garlic, and prepared mustard into the bowl of a high-capacity food processor.

Pulse the machine continuously until the dairy proteins break down and unify into a completely smooth, thick cream base.

Add the flaked salmon, chopped fresh parsley, fresh dill, onion powder, and garlic powder directly to the processor bowl.

Pulse the machine repeatedly until the salmon is fully integrated and the mixture becomes light, pale pink, and highly aerated. (Do not overprocess into a pure liquid; retain a slight, rustic texture).

Stop the machine, taste, and season aggressively with the kosher salt and coarse black pepper. Pulse one final time to combine.

Transfer the salmon mousse to a professional pastry bag fitted with a large star tip (or an airtight container if serving as a dip).

Refrigerate for a minimum of 30 minutes. This critical thermal resting phase solidifies the cream cheese, locking the airy structure in place for flawless piping.

To serve, pipe the chilled mousse heavily into the hollowed cherry tomatoes, celery sticks, and onto the cucumber rounds. Serve immediately.