Flounder has got to be my favorite fish - delicate and delicious it deserves to be on the same pedestal as the whitebait.
I remember - when hitchhiking once - a Maori bloke telling me that snapper was shit fish - he just ate flounder - yellow belly flounder at that. He was specific - others not so. After drag netting on Waikanae beach once I ended up with half a dozen sole - which impressed an average Kiwi bloke. I told them that they were 'sole' - he just said 'they're all flounder though - in't they!'.
Here are some pictures of New Zealand flatfish to help:
There is also the Lemon Sole - but I have not caught these so left out.
Look there are two established methods for cooking Flounder - whole or filleted.
If I catch half a dozen or more - I fillet - lightly flour and fry in butter - and serve with a pinch of Maldon Sea Salt and a squeeze of fresh lemon.
If I only catch a couple - I'll pan fry whole - and make a garlic lemon sauce.
Either way - they are my favorite seafood.
Also - don't ever buy frozen flounder - yuk - what a waste of good fish!