Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Place the broccoli florets and trimmed asparagus spears on the baking sheet, drizzle with half of the avocado oil, and sprinkle with the garlic powder and a pinch of sea salt.
Toss the vegetables thoroughly to ensure even coating and roast in the oven for 12-15 minutes until they are tender and slightly charred at the edges.
While the vegetables are roasting, pat the salmon fillet completely dry with a paper towel to ensure a proper sear, then season the flesh side with the remaining sea salt and black pepper.
Heat the remaining avocado oil in a stainless steel or cast iron skillet over medium-high heat until the oil is shimmering but not smoking.
Carefully place the salmon skin-side down in the hot pan and press down gently with a flexible spatula for 10 seconds to prevent curling; sear for 4-5 minutes until the skin is golden and crispy.
Flip the salmon carefully and cook for an additional 2-3 minutes on the flesh side until the center is just opaque and the internal temperature reaches 135-140°F.
Remove the salmon and roasted vegetables from the heat, plate them together, and finish with a fresh squeeze of lemon juice over the entire dish before serving.