Place cauliflower florets and peeled garlic cloves in a steamer basket over boiling water and steam for 10-12 minutes until very tender.
While cauliflower steams, trim the woody ends off the asparagus and set aside.
Pat the salmon fillet dry with a paper towel and season with salt and pepper.
Heat olive oil in a non-stick skillet over medium-high heat.
Place salmon skin-side up in the pan and sear for 4-5 minutes until a golden crust forms.
Flip the salmon and cook for another 3-4 minutes until cooked through to your preference.
In the last 4 minutes of the salmon cooking, add the asparagus to the steamer basket with the cauliflower.
Transfer the steamed cauliflower and garlic to a blender or use an immersion blender to process until smooth and creamy, adding a splash of water if needed.
Plate the garlic mashed cauliflower, top with the seared salmon, and serve the steamed asparagus on the side.
Finish the dish with a fresh squeeze of lemon juice over the salmon and asparagus.