For the marinade and fish: Combine all the marinade ingredients in a small bowl. Pour the marinade into a plastic zipper-lock bag. Put the salmon steaks into the bag, seal it, and marinate the steaks in the refrigerator for at least an hour.
For the dressing: When ready to cook the salmon, whisk all the ingredients (except seeds) together in a small bowl until combined, then set aside.
Heat a large nonstick skillet until hot. Remove the salmon steaks from the marinade and arrange them in the hot skillet with the marinade on top. Cover and cook over medium to high heat for about two minutes, or until the bottoms of the steaks are nicely browned and the tops are cooked through from the steam created in the covered pan. The steaks should be slightly rare in the center.
Serve the salmon steaks with the lemon dressing drizzled over and around them and sesame seeds sprinkled on top. Make ahead: For this fast, easy recipe, the salmon can be marinated in the refrigerator overnight.