Instructions

1. Place the flounder on a clean cutting board with its dark side facing up. Feel for a hard bony ridge, called the gill plate, where the head joins the body. Make a semicircular cut with your knife tip, reaching underneath the gill plate to separate it from the fillets. Skip this if the fishmonger already removed the head.

2. Press your fingers lightly to the middle of the flounder, feeling for the dividing line where its muscles meet the backbone. Position the tip of your boning knife where that dividing line meets the gill plate, just behind the flounder's head. Cut through the skin and down to the bone, feeling for the bone with the tip of the knife. Draw the knife the length of the fish, following the line of the backbone, slicing through the skin and flesh.

3. Slide the tip of your knife back into that first cut and turn it to a horizontal position. Slide it along the flounder's bones until it reaches the skin at the outer edge of the fish, then draw your knife blade all the way back to the tail. The fillet should come away neatly, still connected to the flounder by the skin. Cut through the skin to release the first fillet.

4. Repeat that same process from the other side, to free your second fillet. Reverse the fillet and start at the tail end if you find it easier, rather than cutting in the "wrong" direction.

5. Turn the fish over, and locate the center line on its underside. Make an initial lengthwise cut, as you did with the top side of the flounder, then the same horizontal cuts to remove the two fillets.

6. Skin the fillets, if desired, by holding the tail end of the fillet in place on your cutting board and slicing down diagonally to the skin. Turn your knife blade until it's nearly horizontal, and slide it between the flounder's flesh and skin to separate them. Repeat for the remaining fillets.