Step 1: Find a Flounder
These fish are flat (surprise!), and adults carry both eyes on the darker top side of the head. They tend to spoil quickly, so eat them soon after you catch them or make sure to buy one in very good condition. There should be no fishy smell, the flesh should spring back when you prod it, the eyes should be clear, and the gills bright.
Step 2: Clean Your Fish
Cut the head off, making sure to leave as much of flesh as possible on the body, but cutting the gills and pectoral fins off with the head.
Remove the guts through the forward opening. If you have problems getting everything out, cut a slit along the fish's length for better access.
Rinse the fish, and pat dry.
Step 3: Starch and Spray
Spray a baking dish with canola oil, add your fish, then spray the top side of the fish with canola oil.
Step 4: Season
Step 5: Broil
Remember that this is a rather thin fish, and that it will continue to cook after you remove it from the oven! It's always better to undercook fish than to overcook it, as you can always pop it back under the broiler.
Let the fish cool for about 5 minutes, then check to make sure the thickest part is cooked. It should flake easily with a fork or thin knife.
Step 6: Serve
There will be small bones to remove, so provide a bone bowl to prevent them from getting lost on the plate and caught up in other dishes.
You can also get flounder fillets, but I really enjoy eating my fish whole. It's a bit more work at the table, but the flavor is better, the fish is fresher, and they're less likely to overcook than fillets. Take your pick.