Heat olive oil in a large cast-iron pan. Place salmon fillets in the hot oil flesh side down. Do not move the fillets, allow them to cook for approximately 3 minutes to create a sear on the flesh.
Gently turn the fillets over so they are skin side down. At this time spoon the Sriracha Horseradish sauce over each fillet. Cover with a lid for about two minutes to allow the steam to Cook the sauce onto the top of the fish.
Remove the lid and continue to cook until the exterior is firm and the interior is moist. Approximately 3 to 5 minutes (this time depends on the thickness of your fillet.)
Salmon should not to be overcooked as it will be dry.