Preheat the oven to 350°. Place the salmon in a medium baking dish and bake, covered, until cooked through, about 15 minutes. Let stand until cool. In a medium bowl, combine the cucumber, bell pepper, scallions and lemon with 3 tablespoons extra-virgin olive oil. Add the baked salmon, flaking the meat with a fork, and mix until combined. Season with salt and pepper.