Preheat your oven to 400°F and line a baking sheet with parchment paper.
Trim the woody ends off the asparagus and toss the spears with half of the olive oil, salt, and pepper.
Spread the asparagus on the baking sheet and roast for 12-15 minutes until tender-crisp.
While the asparagus roasts, steam the cauliflower florets until they are very soft, about 10 minutes.
Transfer the steamed cauliflower to a blender or food processor along with the Greek yogurt, garlic, and a pinch of salt, then blend until completely smooth.
Season the salmon fillet with salt and pepper.
Heat the remaining olive oil in a non-stick skillet over medium-high heat.
Place the salmon skin-side down in the pan and sear for 4-5 minutes until the skin is golden and crisp.
Flip the salmon carefully and cook for another 2-3 minutes until the fish is opaque and flakes easily.
Spoon the cauliflower mash onto a plate, top with the seared salmon, and serve alongside the roasted asparagus.