A runny egg yolk is a thing of pure beauty. Place one on top of almost any dish, and that dish is better. Put it on top of leftovers, and those leftovers become breakfast. It's buttery without the butter, cheese-y without the cheese, and all around good, good, good. But alas, egg yolks are not all that portable in their runny form. If you have a sous vide handy, you could turn them into a runny egg yolk sauce to drizzle over everything. But if you lack such technology, there is far simpler way to turn those golden blobs of goodness into something that's a little bit more portable. They have the taste of a runny egg yolk, the texture of a medium-firm cheese, but the transportation ease of a hard-boiled egg yolk. You just need salt, sugar, and time. I speak, of course, about cured egg yolks.
Cured egg yolks operate on the same principle as gravlax, and, well, most other cured meats. basically you plonk those little yolks in a bed of salt and sugar (carefully, otherwise, you know, what you have is just a tray of really salty, sugared, raw scrambled eggs) and wait for them to dry out. You can speed up the process by leaving them in an oven turned to a very low temperature, or in a turned off oven for a bit. It is one of those things that sounds complicated but is shockingly easy—you just leave it alone and then happen upon it again in a couple days. (This is the best recipe I've found for curing egg yolks, but honestly, once you get the basic idea, it's pretty easy to wing.) When the yolks emerge from the curing process, after you extract them from the salt and sugar, you can grate the egg yolks over anything you please. Salads? Yes, indeed it is quite good that way. Pasta? Oh sure. Soup? I can't see why not. Other eggs? Go ahead and give the inception omelet a run for its money, I'm sure Justin Warner would approve.
But besides being a good way to carry around a runny egg yolk without fear of salmonella or a complicated Tupperware situation, cured egg yolks are a crazy good party trick. Show up to a party with a bag of egg yolks and people will look at you like you're a wizard. Bust one of those out with a grater when you're making dinner, and your friends will be impressed. But cured egg yolks are delicious, easy, and just plain cool. Go forth and make some.