Instructions:
To make the sauce, first make the 2 cups of vegetable broth with bouillon or however you're doing it. Bring it to a boil. Add in the Mirin, the soy sauce, and the seasoning. When heated, pour into little dipping dishes for each person. Eat the noodles by scooping up a chopstickful and dunking it in the dipping cup, then slurp it up.
Note: This sauce is in no way a traditional zaru soba sauce. I've changed it extensively from some other recipes I've seen, because I'm vegetarian and limited in my abilities to find certain ingredients anyway (as I don't live in Japan). This sauce is untraditional but tastes great with the cold noodles!