I used a lull in between rain storms to venture out and have a look at the Sunday fish stock at a neighborhood grocer.  The only thing decent they had was makokarei (below “karei”), or young marbled soles that were shipped fresh from Chiba prefecture.

Prepped sole (karei) with head and guts removed.

About a 10 inches in length and weighing about 380 grams, this flatfish was not exactly a bargain at 752 yen ($9.64). But when these babies are available, I won’t waste the opportunity for a nice meal in the form of sushi, sashimi, or grilled sole.

Karei are a white meat fish and have a light taste that when properly served can have a slightly fluffy texture, especially when grilled, broiled or otherwise cooked.

The sushi and sashimi iterations present an unexpectedly tough and chewier texture compared to the cooked versions. Karei and its opposite-eyed cousin the Hirame (Flounder) are popular choices at restaurants that specialize in fish — but they are also more expensive compared to more common fish like aji (horse mackerel) and sake (salmon).

I sliced my sole at home (I had the fish seller remove the head and guts before repackaging) using the Gomai-oroshi or five-piece fillet method. Like the name suggests, the result is 4 boneless fillets and a bony carcass (not pictured) — the fillets I used for sushi and frying, while I threw the leftovers into a pot for soup.

When filleting a flatfish, make sure you have a thin and flexible fillet knife or other chef’s knife with a slender blade. It also helps to rinse and wipe your blade during the filleting so you can make a clean cut as often as possible — this will help prevent tearing or ripping of flesh and possibly ruining your fillets.

Sole fillets after using gomai-oroshi (5-piece fillet). Carcass (the fifth piece) is already in the soup pot!

Picking a good flatfish (sole or flounder) is not difficult, but what is difficult is finding one that isn’t cultivated (“farmed”). I personally preferred freshly caught flatfish because while I have a general idea of what these bottom-feeders dine on in the wild, I don’t want to think about the stuff the farmers are giving them in the cultivation ponds. Not that it’s easy to taste the difference either, but it is just for peace of mind.

Farmed soles and flounders can be spotted very easily by flipping them to see the white underbelly and checking for dark spots on the skin. I have been told that the feed used in cultivation causes this, but I will save the science behind that for another time. The point is, if you want a fresh flatfish, go for a pure white underbelly specimen — don’t forget to ask the salesman if it’s not indicated.  Most supermarkets and fish mongers know that more and more people have become aware of the difference between fresh and farmed fish and may likewise develop a preference for the fresh version.  So, they sell their flatfish in packages with the fish’s white underbelly in full visibility.  I think this is great because not only does it show honesty on the part of the seller, but it prevents too many people from messing with the fish too many times to check for spots — someone eventually needs to buy that fish and it’s best that it’s not been handled too much!

You know that sleepy feeling you get after eating a big turkey dinner?  It’s not just because you ate too much (but might be a contributing factor), but thanks to a natural substance called Tryptophan, which is found in many foods including turkey, nuts, and legumes.

Tryptophan, specifically L-Tryptophan, is one of the essential amino acids and aids in the body’s production of serotonin (for healthy sleep). Find out more about why it makes you so drowsy on Wikipedia.

After a little more research, I found that tuna, scallops, salmon, sardines and halibut also contain Tryptophan.  I wonder how many pieces of maguro, hotate, sake, iwashi and ohyo (karei) sushi it would take to put you under?  But, does anyone know if it matters that the fish is raw when eaten?

Well, there is only one way to find out. The next chance I get, I’ll focus on eating mostly sushi made from fish species that I know to contain L-Tryptophan — I’ll skip the beer.

If anyone knows more, I’d be happy to hear about your experiences! I’ll follow up with my own in a later post down the line!