1. Gather your materials: To clean a flounder, you will need a sharp fillet knife, a cutting board, a scaling tool or fork, and several paper towels.

2. Prepare the work area: Make sure your work area is clean and well-lit. Place the cutting board on a non-slip surface to prevent accidents.

3. Kill the fish humanely: If your flounder is still alive, use a quick and humane method to kill it before cleaning. One option is to place it on ice until it becomes unconscious, then swiftly sever the spinal cord behind the gills with your knife.

4. Rinse the flounder: Rinse the fish under cold running water to remove any debris or slime.

5. Scale the fish: Using a scaling tool or fork, remove the scales from both sides of the flounder. Doing this step first makes it easier to handle the slippery fish during filleting. Be sure to scale away from yourself to avoid injury.

6. Cut off the head: Place the flounder on your cutting board with its dark side facing up. Locate the gill plate and use your knife to make a shallow cut from just behind the gill plate toward the tail of the fish, severing both sides of its head in one smooth motion.

7. Make a vertical incision: With your knife held at a slight angle, make an incision down the center of the flounder’s body from just below the collarbone to its anus.

8. Remove internal organs: Carefully scoop out and discard any internal organs located within the body cavity.

9. Fillet the flatfish: Begin by making an incision near where you removed the head; slice along one side of the backbone towards the tail, staying as close as possible to keep as much meat as possible on each fillet. Repeat this step with the other side, creating four fillets in total (two from each side of the fish).

10. Clean up and store: Rinse your four flounder fillets under cold water to remove any debris or traces of organ material. Pat them dry with paper towels and store them in an airtight container in the refrigerator until you’re ready to cook.

By following these 10 steps, you’ll be able to clean and prepare fresh flounder for a delicious and satisfying meal.