Mentsuyu udon, but the sauce is different and I’m obsessed.

Last week at a wonderful little spot in Irving, I had this delicious cold udon dish which I since have realized is called mentsuyu udon. What got me is the sauce. It was very ammonia-y, full of umami and salty. Not like any fish sauce or soup base or ponzu sauce or anything I have ever encountered. I wouldn’t even know where to begin to replicate it. I’ve cooked with items listed in the mentsuyu recipes I’m finding, but none of those flavors fully replicate this at all. My boyfriend has worked as chef and said he believed it could be made from a higher quality fish sauce than we are used to seeing but it was so very different from anything I’ve encountered and I usually have a good pallet. I’m grateful for any leads. 🙂