Preheat the oven to 325°F (160°C).
Coat a baking tray with cooking spray. Arrange the slices of rye bread in a single layer on the baking tray. Spray the tops of the slices lightly with cooking spray. Bake for 12–15 minutes or just until the slices are crisp.
Whisk the lemon juice, tea (or vodka), oil, mustard and pepper in a medium bowl. Add the smoked salmon, red onion, dill and capers. Toss to mix well.
Shortly before serving, mound about 1 tablespoon of the smoked salmon topping on each slice of toast. Garnish each with a dill sprig.