Scrub the Yukon gold potatoes and dice them into small, uniform 1/2-inch cubes to ensure even cooking and maximum crispiness.
Heat the avocado oil in a large non-stick or cast-iron skillet over medium-high heat until shimmering.
Add the diced potatoes to the skillet and season with half of the sea salt, black pepper, and garlic powder.
Cook the potatoes for 8-10 minutes, tossing occasionally, until they are golden brown and tender on the inside.
While the potatoes cook, pat the salmon fillet dry with a paper towel and season both sides with the remaining salt, pepper, and garlic powder.
Push the potatoes to one side of the skillet and place the salmon fillet skin-side down; cook for 4-5 minutes until the skin is perfectly crispy.
Flip the salmon and add the asparagus spears to the empty spaces in the pan, cooking for another 3-4 minutes until the salmon is flaky and the asparagus is bright green.
Remove the skillet from the heat, drizzle the fresh lemon juice over the salmon and vegetables, and serve immediately.