Wash salmon filets and place salmon on a paper-towel lined plate to dry for 5-10 minutes per side. Season salmon with salt and pepper, flip over and season the next side with salt and pepper
Pour oil in a large pan/skillet. Heat over high heat. When hot, add salmon skin side down. Cook 4-5 mins, until skin is crisp. Flip and cook other side, about 4 mins, until salmon registers about 120 F. Cook longer if you desired, but remember fish continues to cook a little after you remove it from the pan.
Remove salmon from pan and set aside. In the same pan add onions and cook about 3 minutes, until tender. Pour in coconut milk and parmesan, juice from 1 lemons (start with 2 Tbsp, then add more if you love lemon) and rosemary, then stir to combine. Taste sauce and adjust seasoning as needed.
Remove from the heat, then return salmon filets to the pan.
Serve immediately with your favorite veggies or whatever you desire.