Place all of the ingredients for tapenade in the food processor and process to a coarse paste, without letting it get mushy. (You can store the tapenade in the fridge for up to three days.)
Heat the oven to 350°F. Put salmon in one layer in a roasting pan, skin side down. Drizzle with 3 tablespoons oil and lemon juice. Lightly season with salt and pepper. Bake in the oven until the salmon is just cooked through the center, about 20 minutes, depending on the thickness of the filets.
Transfer to serving and top the filet with tapenade. Serve with a lemon wedge.