Preheat the oven to 425°F and line a baking sheet with parchment paper.
Prepare the asparagus by trimming the woody ends and tossing them lightly with a pinch of salt, pepper, and a drizzle of olive oil.
Place the asparagus on the prepared baking sheet and roast in the oven for 10-12 minutes until tender and slightly crispy.
Meanwhile, steam the chopped cauliflower until very tender, about 8-10 minutes.
Once the cauliflower is soft, transfer it to a bowl and mash with a teaspoon of olive oil, a pinch of salt, pepper, and garlic powder to taste, until you achieve a smooth texture.
Heat a non-stick skillet over medium-high heat. Season the salmon fillet with salt, pepper, and garlic powder.
Sear the salmon, skin-side down first if the skin is on, for about 3-4 minutes until a golden crust forms. Flip the salmon and cook for an additional 3-4 minutes until the fish flakes easily with a fork.
Plate the seared salmon alongside a serving of roasted asparagus and a generous scoop of cauliflower mash. Serve immediately.