How to Make It
Pat fish dry and season with salt.
Heat a large skillet over medium-high until very hot. Add 1 tablespoon oil; swirl skillet to coat. Carefully add 2 fillets, skin side down (lay them away from you to avoid spattering). Shake skillet to prevent sticking. Press firmly on each fillet to help skin make contact with skillet. Cook, undisturbed, until edges are golden brown, about 4 minutes. Flip and cook until just cooked through, 1 to 2 minutes. Transfer to a plate, skin side up. Repeat with remaining oil and fish.
Serve fish with lemon slices, if using, or one of the sauces ahead.