Restaurant in Tokyo - a Great Sauce

I know this is vague, but we were taken to an old time restaurant in Tokyo by a friend. The food was all served on very thin skewers but was nothing like yakitori. Much of the food consisted of various delicate shellfish and since I am allergic, they made separate little delights for me, many lovely vegetables, etc. My question is this, they served a very dense, thick black sauce with the food that we loved. Can any of you guess what it might have been? It was probably a miso-based sauce, but was nothing like any sauces we had elsewhere in Japan. Thanks for any clues you might have.

It sounds Miso-dare(Miso sauce)
Its used for fried food, ex. Cutlet, skewers.
Its taste and color of sauce varies on the miso and material(Soy sauce, stock), salty, sweet and black, brown, light brown.
Sesame and some herb/spice might be used.

If it tasted like miso, then it must be miso-dare. But at a skewer (kushi yaki) restaurant, I would expect to be served a thinner vinegar based (pon-zu, etc.) sauce so I was thinking you had a form of teriyaki.
I know teriyaki food/sauce isn't that common in Japan as it is outside of Japan, but I've eaten a similar dark thick sauce that was on the border between teriyaki sauce, miso-dare sauce, and tonkatsu (porkchop) sauce. But it was at a tonkatsu place...
What you ate could have been one of those or a mix - or something the restaurant where you ate at whipped up themselves.