Place the baguette slices on a baking sheet. Brush them with olive oil, and lightly sprinkle them with salt. Bake for about 4 minutes, until golden around the edges, but not hard – they will firm up as they cool. Let them cool to room temperature.
Raise the oven temperature to 425°F. Line a rimmed baking sheet with foil or parchment, and spray with nonstick cooking spray.
Cook the salmon: Place the salmon filets skin side down on the prepared baking sheet and drizzle about ½ teaspoon of olive oil over each piece and use your fingers to rub it over the top and sides. Season with salt and pepper. Roast for 8 to 10 minutes per inch of thickness, until it flakes easily and the internal temperature is at least 145°F in the thickest part. Allow to cool to room temperature.
Make the Sauce: While the salmon is cooking, in a food processor puree the parsley, garlic, lemon juice, salt, oregano, and red pepper flakes. With the motor running, drizzle in the olive oil. Scrape down the sides after all of the oil is added, then puree again until everything is well combined. Taste and adjust the salt, and add the black pepper as desired. Set aside.
Peel the salmon skin from the fish and discard. Use your fingers or a fork to flake the salmon into small chunks. Place the salmon in a bowl and spoon over a little over half of the sauce. Toss gently to coat the salmon with the sauce. Spoon some of the salmon mixture on top of each piece of toast, and drizzle a touch more chimichurri sauce over the tops.