Place salt, sugar, and porcini powder in a bowl and whisk to combine.
Pour half of the salt, sugar mixture into a small casserole dish in an even layer. Using the back of a tablespoon, make four yolk-size indents in the salt, sugar mixture. Gently place yolks in the indents and carefully cover them with the remaining salt, sugar mixture. Mark the location of each egg yolk with a peppercorn and wrap the casserole dish loosely with plastic wrap. Leave the egg yolks in the fridge for 48 hours.
When the 48 hours is up, carefully remove the egg yolks from the salt, sugar mixture and place them on a cooling rack. Pop the egg yolks in a 150 F oven for an hour and a half. Place finished egg yolks in a jar and refrigerate until ready to use. Cured egg yolks will keep for up to a month.
For the Wild Mushroom Miso Risotto
Place dried mushrooms in a medium-sized mixing bowl. Add the warm water and leave the mushrooms to reconstitute for at least 20 minutes or for up to an hour. Once the hour is up, drain the mushrooms and reserve the liquid.
Prepare the dashi according to the package's instructions. Reduce dashi to a simmer and stir in the reserved mushroom water and miso paste. Leave to simmer.
In a dutch oven, heat olive oil over medium heat. Add garlic and saute until fragrant. Add rice and reconstituted mushrooms to the pot and stir until the rice begins to crackle.
While stirring constantly, add sake, and cook until there is almost no moisture left. Add just enough miso soup to the rice to barely cover it. Cook, stirring constantly until the soup has almost disappeared. From here, add a ladle or two of the miso soup to the rice at a time, until the soup is gone and rice is smooth and creamy with a slight bite. Remove from heat.
Garnish the risotto with sesame seeds and grated cured egg yolk. Serve immediately.
Notes
**To make mushroom powder, simply grind up a pack of dried porcini mushrooms in a food processor or coffee grinder.