Add the yogurt (preferably a thicker yogurt like Greek, also works with vegan alternatives like soy), tahini and lime juice to a bowl and stir them together. Add salt and pepper to taste.
If you're going for the vegan option, stir in the nutritional yeast. Besides nutritional benefits, this will also thicken the sauce to resemble greek yogurt somewhat.
Add any of the herbs/gochugaro to your liking. I personally love 1 teaspoon gochugaru and a tablespoon of dried dill, or a handful of fresh chives.
Use it as a dressing on salads, a dipping sauce for naan/flat bread or as a flavorful addition to any warm meals like pasta/couscous. Enjoy :)