Dry filets and salt both sides. Place in a pan on a rack and refrigerate for 1 hour.
Butter the fleshy sides with the anchovy butter. Pepper the flesh side. Place the filets on top of each other, skin side out. Oil the skin side
Place on a hot pan for a few minute till the skin is crispy. 3 minutes maybe
Flip to crisp the other skin side. Another 2-3 minutes
Remove and let rest. Squeeze some lemon on top if you want.
Make a beurre blanc sauce. (Optional)