But as weird as is sounds you can use ketchup... like a small glob of ketchup. 10ml/500ml of water. ketchup has umami from the tomato's glutamic acid and it also has salt, sugar and vinegar in the ingredients so it houses various flavours.
I tried it once and you get a hint of ketchup but then again i didn't follow the measurements and just randomly added some amount.
Just add a bit and taste test as you go along.Iit's better than just having only miso and water.
Throw in some sliced shiitake too it can't hurt;-)|||Try posting your question in "food" and not language.