Pat the barramundi fillets completely dry with a paper towel to ensure a crispy skin.
Season both sides of the fish evenly with sea salt and black pepper.
Heat the avocado oil in a large stainless steel or cast iron skillet over medium-high heat until shimmering.
Place the fish in the pan skin-side down and press gently with a spatula for 30 seconds; sear for 4-5 minutes until the skin is golden and crispy.
Carefully flip the fillets and cook for another 2-3 minutes until the fish is opaque and flakes easily. Remove fish from the pan and set aside.
In the same pan, add the minced garlic, asparagus spears, and cauliflower rice; sauté for 3-4 minutes until the vegetables are tender-crisp.
Move the vegetables to the side of the pan and add the ghee, lemon juice, lemon zest, and fresh parsley, whisking quickly to create a light sauce.
Plate the cauliflower rice and asparagus, top with the barramundi, and spoon the buttery lemon-herb sauce over the top.