How to Make It
Preheat the oven to 375°. Lay the salmon skin side down on a rimmed baking sheet and season with salt and pepper. Bake for about 20 minutes, until just cooked through. Let cool, then flake into large chunks; discard the skin.
Meanwhile, in a small bowl, whisk the buttermilk with the olive oil and poppy seeds. Season the dressing with salt and pepper.
Arrange the salmon, oranges, grapefruit and avocado on a platter or plates. Drizzle some of the dressing on top. Garnish with snipped chives and serve, passing additional dressing at the table.