If anything could get me to believe in a higher power (and the fact that they have a sense of humor), it’s the existence of eggs. They’re a perfect food (that we get from the butt region of a mostly flightless bird). The high-protein white, coupled with a luscious, vitamin-packed yolk makes it a versatile, nourishing food. I will admit that the yolk is my favorite part, though only a real sicko would prefer the white. The yolk is where the flavor is, and you can concentrate that flavor even further by making soy sauce cured egg yolks, for a soft, savory, spreadable yolk.
How to cure an egg yolk with soy sauce
Soy cured yolks are popular in both Japanese and Korean cuisine, and often found on steaming bowls of hot rice. Soy-sauce curing is pretty similar to salt curing, only the salt is dissolved in a liquid (soy sauce) instead of in its crystalline form. That doesn’t matter a whole lot, however, because osmosis occurs either way. A higher concentration of the solute (salt) on one side of a semi-permeable membrane (the vitteline membrane, in this case) causes the solvent (water) to flow toward the region with a higher concentration of the solute, in an attempt to equalize the concentrations on each side of the membrane.
The water flows out of the yolk, concentrating its flavor and giving it a firmer texture, while the soy sauce seasons the yolk, resulting in a jammy, savory disc that’s equally at home in a bowl of hot rice or on top of leftover pizza.
How long does it take to soy-cure an egg yolk?
Unlike dry curing, which dehydrates the yolk into something that can be grated like cheese, wet curing is a faster process, with a softer, more spreadable outcome. (You could probably get similar results from a dry cure, but it would be difficult to free the yolk from the salt mixture without breaking the yolk.)
After four hours of soy curing, the yolk will be lightly firm at the very edges and still liquidy in the center, with a lightly salted, savory flavor. After eight hours, it will be a little firmer and a little saltier. After 24, it’s firm but spreadable, and quite salty, depending on how much soy sauce you used (and how much of everything else), but there is no one “right” cure time. Play around with the timing and find your favorite.
How much soy sauce do you need?
The soy sauce is the most important ingredient in soy-cured egg yolks, as it contains the salt that is needed for osmosis to occur, but a curing bath of all soy sauce will leave you with a powerfully salty yolk, especially after an extended soak.
To temper the salinity and add some sweetness, you can add a little mirin (Japanese cooking wine). If you want to add even more flavor, you can add other ingredients like ginger, garlic, kombu, and bonito flakes. If you want your yolks to have a pickled quality, you can make shoyozuki (soy-pickled) yolks, using a ratio of one part vinegar and two parts soy sauce, along with a little sugar.
Easy Soy Cured Egg Yolks
Ingredients:
8 egg yolks
1/2 cup soy sauce
1/4 cup mirin
Optional: Freshly grated ginger, chopped garlic, or finely sliced scallions
Combine all ingredients in a small bowl and pour into a shallow dish that will accommodate 8 yolks. Slip the yolks into the curing solution, and place a paper towel on top so the yolks are fully covered by the curing mixture. Set in the fridge for 4-24 hours, depending on your preference. (I recommend starting in the 8-hour region.)
Fish the yolks out with a spoon and spread them on toast (or pizza), plop ‘em on a rice bowl, or add them to some ramen. They’re also nice on a salad, both green and deli. (Just imagine a potato salad with a jammy, savory yolk mixed in. I did, and it made me happy.)
Once you’re satisfied with your cure time, try adding in other flavors, like ginger, garlic, bonito, dashi, or chili flakes, and play around with the soy sauce. Japanese, Chinese, and Thai soy sauce all have different flavor profiles, and if you want to get really wild, you can try swapping it out for fish sauce for something a little funkier. If your yolks come out too salty for your liking, just mix them in to a bowl of plain rice, letting the yolk act as seasoning for your overall dish. Then try it again, adjusting your ratios and timing until you land on a texture and flavor that thrills you.