Preheat the oven to 275F (low and slow!) .
To make the chimichurri, in a high-speed blender, add the parsley, oil, vinegar, rosemary, salt, pepper, and garlic and blend until smooth, scraping down the sides as needed (start off at a low speed and increase to high).
Drizzle 2 tablespoons oil into a large baking dish and spread around to coat. Add half of the lemon and orange slices on the bottom in one or two strips (to lay the salmon on top of, see photos). Place a sprig or two of rosemary on top of the citrus slices. Place the salmon on top and sprinkle with enough salt to lightly coat the salmon. Top with 3 tablespoons worth of chimichurri, spreading it around to coat. Arrange remaining citrus slices on top of the salmon.
Bake for 30-40 minutes, or until cooked through and easily flaked with a fork (depends on salmon thickness, the salmon I used was relatively thin).
Remove the citrus slices and use two forks (or your hands) to flake the salmon into chunks, arranging the citrus slices among the chunks (I like this best because it’s pretty and easier to serve). Drizzle the remaining chimichurri over top (or keep it on the side, up to you!).