Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Peel the sweet potato and cut it into uniform 1/2-inch cubes to ensure even cooking.
Place the sweet potato cubes on the baking sheet, toss with 0.25 tbsp of olive oil and a pinch of sea salt, then roast for 15 minutes.
While the potatoes roast, trim the woody ends off the asparagus spears and pat the salmon fillet completely dry with a paper towel.
Add the asparagus to the baking sheet with the sweet potatoes, tossing to coat in the residual oil, and roast for an additional 10 minutes.
Season the salmon fillet on both sides with sea salt, black pepper, and garlic powder.
Heat the remaining 0.25 tbsp of olive oil in a heavy-bottomed skillet over medium-high heat until shimmering.
Place the salmon skin-side down in the pan and press gently with a spatula for 10 seconds to prevent curling.
Sear the salmon for 5 minutes until the skin is golden and crispy, then carefully flip the fillet.
Cook for another 2-3 minutes until the fish is opaque and flakes easily with a fork.
Remove the roasted vegetables from the oven and plate them alongside the salmon.
Finish the dish with a fresh squeeze of lemon juice over the salmon for a bright, acidic pop.