Scrub the Yukon gold potatoes and cut them into 1/2-inch cubes.
In a small bowl, toss the potato cubes with 1/4 tbsp of olive oil, dried rosemary, garlic powder, and half of the salt and pepper.
Place the potatoes in the air fryer basket in a single layer and cook at 400°F for 15-18 minutes, shaking halfway through, until golden and crispy.
While potatoes cook, season the salmon fillet with the remaining salt and pepper.
Heat the remaining 1/4 tbsp of olive oil in a non-stick skillet over medium-high heat.
Place the salmon in the pan, skin-side down, and sear for 4-5 minutes until the skin is crispy.
Carefully flip the salmon and cook for another 2-3 minutes until the internal temperature reaches 145°F.
Steam the asparagus spears for 3-4 minutes until tender-crisp and bright green.
Plate the salmon alongside the air-fried potatoes and asparagus, finishing with a fresh squeeze of lemon juice.