Preheat oven to 425°F. Line a baking sheet with parchment paper for the asparagus.
Trim the asparagus ends and toss them with a pinch of salt, black pepper, and half of the olive oil. Spread them evenly onto the baking sheet.
Roast the asparagus in the preheated oven for about 12-15 minutes until tender and slightly charred.
Meanwhile, break the cauliflower into small florets and steam or boil until very tender, about 10 minutes.
In a blender or food processor, combine the cooked cauliflower with garlic powder, a pinch of salt, and the remaining olive oil. Blend until smooth and creamy. Adjust seasoning as needed.
Pat the salmon fillet dry with a paper towel and season both sides with salt and black pepper.
Heat a nonstick skillet over medium-high heat. Once hot, sear the salmon, skin-side down if applicable, for about 3-4 minutes until a golden crust forms. Flip the salmon and cook for an additional 3-4 minutes, or until just cooked through.
Plate the salmon alongside a serving of roasted asparagus and a generous scoop of cauliflower mash.
Garnish the salmon with a fresh lemon wedge for squeezing over. Serve immediately.