Rex Sole
Rex Sole [Glyptocephalus zachirus]

This righteye flounder is caught in the North Pacific from Southern California to the Russian coast and down to Taiwan. The can grow to 23 inches and a bit over 4 pounds, but the photo specimen was 15-5/8 inches long and weighed 1 pound 1-1/4 ounces, typical in the markets here. Rex Sole and Gray Sole are often confused in markets, but the rex has a very long pectoral fin and the gray a very short one. The population is not considered threatened, Red List status NE (Not Evaluated).

Fish Page

Outline fillet
Outline fillet
Filet half
Fillet half side
Recipe Ready

Pan Ready

Cut spine
Cut Backbone
Cleaned - easy!
Remove fins
Remove fins
Pan fried
Pan fried
Removing rays
Removing fin rays

The flesh of Rex Sole is white, tender, fine grained and mild. This fish is an excellent substitute for the once common Sanddab, a lefteye flounder that lives in shallower water, but is now scarce in markets due to fishery regulations aimed at protecting rockfish.

Because it's inconvenient to fillet small fish, rex sole is usually sold either whole or "pan ready" (head, innards, tail and fins removed). Our Pan Ready Method covers making fish "pan ready" and cooking them in that form.

For some uses a pan ready fish is fine if properly handled, but for other recipes a pan ready fish just won't work - it'll fill the food with hundreds of tiny bones. for these uses you must fillet. Rex Sole isn't difficult to fillet but get the biggest fish you can to make it easier - Fillet Method.

Yield:   A 1 pound 1-1/4 ounce fish yielded 8-1/2 oz of skin-on fillet (49%), 4-5/8 ounces from the eye side and 3-7/8 ounces from the blind side. This fish yielded 6-1/2 ounces skin-off. Don't attempt to skin fillets, you'll likely just break them up. The skin is very thin and normally left on. If you pan fry a fillet "skin-on" the skin will shrink a little but then relax as it cooks.

Stock:   The head bones and fins make a fairly substantial soup stock due to the gelatinous nature of the fin area. It is moderate flavored and usable There's a fair amount of oil which should be removed using your gravy separator.

Fillet Method for Rex Sole

Note that the photos in the left column are actually Gray Sole, but the Rex and Gray are totally interchangeable (and often wrongly labeled), so they are valid for both fish.

  1. Scale the fish. Rex sole is covered with very tiny scales and the shape of the fish makes it difficult to scrape with the back of a knife as for other fish, but I find the toothy edge of a grapefruit spoon works just fine.
  2. Clean the fish. Make a small cut on the blind (white) side and use your littlest finger to pull the innards out - OR - just remove the head with the innards as shown in the procedure for Pan Ready
  3. Make a cut along the centerline deep enough to cut all the way to the backbone. The fillet is going to break in half anyway so we might as well make our work easy. Make the usual cuts under the front fins and collar to release the fillet from the head, and make a cut at a very shallow angle along the fin edges as shown.
  4. Fillet from the centerline out following the bones. Should you accidentally get under the fin rays at the transition (quite likely on the thinner blind side) you can just deepen your fin edge outline cut until it meets the main cut.
  5. You should end up with 4 long narrow fillets and bones with very little flesh adhering to them.

Pan Ready Method for Rex Sole

Note that the photos in the left column are actually Gray Sole, but the Rex and Gray are totally interchangeable (and often wrongly labeled), so they are valid for both fish.

  1. Scale the fish as per Fillet Method.
  2. Make a cut under the collar and front fins as you would for fillet. Then take your kitchen shears and cut the backbone from the top just behind the head.
  3. Pull the head away and it'll pull out all the innards with it.
  4. Use your kitchen knife to cut off the fins, cutting just within the margin. No, you can't just cut in farther and remove the fin rays at this point, they overlap the main bones. Cut off the tail if you wish.
  5. You are now ready to cook the fish by any appropriate method. Shown in the picture is steaming and pan frying but broiling would work well too.
  6. If steamed or poached: the skin is likely broken up and unsightly. To remove it just press a paper towel over it, the skin will peel up with the towel. Do not attempt to remove the bottom skin, it's very thin, white, on the underside anyway and traditionally left on.
  7. You could now serve the cooked fish and let the diners deal with the bones, but they'll appreciate not having to. With the fish on your cutting board, best side up, use your kitchen knife to scrape the fin rays away from the fish. Yes, you'll lose a little flesh but the flesh there is kind of gelatinous which some people don't like.anyway.
  8. Serve in whatever way you please. The backbone and it's bones will still be in the fish but they will stay together and be very easy to deal with. There will be no loose bones at all.
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