Place cauliflower florets in a steamer basket over boiling water and steam for 10-12 minutes until very tender.
Add asparagus spears to the steamer during the last 4-5 minutes of cooking until they are bright green and tender-crisp.
Transfer the steamed cauliflower to a blender or food processor, adding the Greek yogurt, ghee, and a pinch of salt and pepper.
Blend the cauliflower until completely smooth and velvety, then keep warm in a covered bowl.
Pat the salmon fillet completely dry with a paper towel and season both sides with salt and black pepper.
Heat olive oil in a non-stick skillet over medium-high heat until shimmering.
Place the salmon in the pan, skin-side down, and sear for 4 minutes without moving it to achieve a crispy texture.
Carefully flip the fillet and cook for another 2-3 minutes until the salmon is just cooked through and opaque.
Spoon the cauliflower mash onto a plate, top with the seared salmon, and serve the asparagus on the side with a fresh lemon wedge.