Several ideas come to mind.
First is lemon butter sauce.
You will need salt and pepper, small amount of all purpose flour, tablespoon of oil, couple of pieces of butter, a lemon, cut in half, remove any seeds you see, and a tablespoon of fresh herbs, basil oregano chives tarragon or parsley, or a combination of available herbs. And a heavy pot cast iron or stainless steel recommended, but use what you got.
Season flounder with salt and pepper to taste,
Lightly dust with all purpose flour, shake off any excess.
Place fish, presentation side down, into a hot pan with a drop or two of oil, cook for a minute or two depending on thickness. Resist the urge to move it around. Leave it still. After the minute or two, flip with the presentation side up. If the fish is sticking to the pan, wait 30 seconds and try again. The pan will release the fish when it is ready to flip. (But you don't want to overcook it). Once it is flipped put a butter pat or two on top the fish and allow the butter to melt into the pan. As soon as the fish is springy to the touch, two minutes or so, remove it to a serving plate. Squeeze a lemon into the pan and deglaze or scrape all the delicious brown bits in the pan mixing the lemon, butter and brown bits as you deglaze. This should only take 15 seconds. Add a tablespoon of chopped fresh herbs. Remove pan from heat, stir to mix, and pour over waiting fish.
Next is one of my favorites, Flounder Almondine.
Optionally follow same directions up to and including using the broiler, without the almonds and cal it Flounder Meuniere.
For this one, many of the same ingredients. Salt pepper, all purpose flour, oil for the pan, butter, lemon, chopped parsley and enough sliced almonds to sprinkle generously over the fish. A broiler is useful.
Season the fish with salt and pepper, coat it fully with flour by dredge in a shallow container of flour to coat and shake off excess. Place fish in hot pan with a touch of oil and brown, flip and finish cooking fully. Place fish on serving plate.
Meanwhile in separate smaller pan, cook 8 one stick of butter until it is light hazelnut brown. Do not over-brown. Squeeze a lemon into the pan, remove from heat, add a teaspoon of chopped parsley. As to your taste, add a pinch of salt or pepper or don't. Stir just to mix.
Generously sprinkle the sliced almonds over the cooked fish, pour enough of your butter sauce, called a meuniere, over the fish to pool onto the bottom of the plate, and place under a hot broiler. Shouldn't take long to toast the almonds. Brown, dark brown, remove at first sign of anything darker than dark brown. Serve immediately.
Lastly a cream creole sauce.
Cook the fish as desired, season then bake, broil, pan saute, fry... your choice.
1 lemon, 1/2 cup worcestershire, 1/2 cup hot sauce (Louisiana brand is my first choice, use something you like, mild pepper sauce is possible, spicy is available). 1/4 cup heavy whipping cream, 4 sticks of butter, salt and pepper to taste. I like white pepper for this one.
Cut the lemon in half, add the lemon halves, worcestershire and hot sauce into a sauce pan. Cook over medium heat until it thickens, stirring constantly.
While whisking, add cream, cook until thickens again, cut the butter into several smaller pieces, adding the butter a piece at a time while whisking adding more butter as the previous piece is fully incorporated. Continue until you use all the butter. It is helpful to use smaller pieces of butter at first, then you can add larger butter pieces as you progress.
Season to taste with salt and pepper. Strain and keep warm for service.
These should give you something to play with for a while. I'm hungry now. Enjoy.