Place the salmon filets into a baking dish, then pour the miso-ginger marinade over them. Be sure to allow the marinade to go under the filets as well.
Put the dish into the fridge and allow the fish to marinate for no longer than 30 minutes.
Preheat a large, well-seasoned, cast iron skillet over medium-high heat to get it very hot. Once you feel the heat radiating off of the surface of the pan- just before it begins to smoke-add the vegetable (or other high-heat oil) to the pan.
Once the oil is in the pan, carefully, lift the pan and swirl it to coat the entire surface of the pan in oil.
Add the salmon filets flesh side down, pressing to make sure the entire surface makes contact with the pan, and sear them for 3-4 minutes.
Use a fish spatula, or other thin, metal spatula to flip the salmon on to the skin side and sear for4-5 minutes to get that salmon skin extra-crisp.
Once the salmon is cooked, remove it to a plate to rest for a couple of minutes, which allows the inner juices to resettle. Garnish with scallions and sesame seeds, if you wish.
Serve on a bed of steamed rice and accompanied with kimchi, pickled radish, mushrooms, more scallions and sesame seeds, and chopped cilantro. Enjoy while hot.