This sauce was stupidly simple and insanely delicious. I served it over a baked sweet potato and Rancho Gordo vaquero beans but I can hardly wait to have it with lamb! I also think it would be really good poured over roasted cauliflower florets not to mention amazingly yummy as a dipping sauce for crushed potatoes with Parmesan or drizzled over roasted vegetables in general.
Quite frankly, if you tweaked the liquid that you used and added spices or heat, this would be a really versatile sauce to add to your repertoire to add to whatever you paired its flavors with.
1 medium-sized white or yellow onion
1 Tbsp red miso
1 Tbsp butter
2 Tbsps very hot liquid (I used dashi, but chicken broth or duck stock would work well, as would vegetable stock or even water with a splash of wine)
1 tsp olive oil
Preheat the oven to 425.
Cut the ends off the onion and rub it all over with the oil. Place it on a foil lined baking tin and bake until soft, about 20-25 minutes.
Squeeze the cooked onion out of its skin into a blender. Add the miso, the butter and whatever liquid you are using and blend until very smooth. The heat from the onion and the liquid will melt the butter which, in turn, will emulsify the sauce.
That's it.