Poach at low to medium heat in vinegar water to defrost and almost cook through, change water once?, then reserve fish, which should be soft and tender
Fry fresh herbs (sage or dill or tarragon) in butter until crispy
Optionally brown the butter slightly
Add minced garlic and fry that too
Flour the fish and fry in the butter (meuniere style), then plate
Pour a bit of butter and the herbs onto the plated fish
Add flour and fry it to make a roux
Add milk, maybe a pinch of nutmeg to make a bechamel