Season the salmon. In small bowl, mix together the oregano, garlic powder and paprika. Use paper towels to pat the fish very dry on all sides and sprinkle all over with salt and black pepper, then rub the spices all over the flesh side of the fish.

Preheat the pan and oil. Heat a large cast iron skillet over medium-high. When the skillet is hot, add enough oil to coat the bottom (about 2 tablespoons) and wait for the oil to shimmer but not smoke.

Sear the salmon. Once shimmering, turn the heat to medium-low and add one salmon filet with the skin-side down. Press the top with a fish spatula for about 10 seconds, which prevents the skin from curling up. Add the remaining salmon filets, one at a time, pressing each with the spatula for 10 seconds.

Don’t disturb the salmon. Cook until the skin is golden and crispy, about 4 minutes. If skin resists lifting (or if it’s sticking to the pan), allow the fish to cook for a little bit longer until you are able to lift up easily, which should take no more than 6 minutes in total.

Flip until cooked through, about 15 seconds. Transfer the seared salmon to a large rimmed plate. Immediately zest on one of the lemons, slice it in half, and squeeze the juice all over.

Make arugula salad. In a medium bowl, add the baby arugula, a pinch of salt, the juice of 1/2 of the remaining lemon, and a drizzle of extra virgin olive oil. Toss to combine.

Serve. Serve the crispy skin salmon with arugula and lemon wedges on the side.