You have what you need, sans the shiso, but you can get it at a Japanese market, or an Asian market. Should be one in SLC.
https://www.yelp.com/search?find_desc=Japanese+Market&find_loc=Salt+Lake+City,+UT
Once you do it it will be easy to make the sauce. It's dead simple. I usually use the darker miso, opposed to the lighter color that seems more typical for South Japan, like Kagoshima area.
My wife uses that one to do a dish called ton-kotsu, which literally translates to pork bones. They cut it flanken, and section it off into individual bone/meat sections. My wife just leaves the spareribs whole and cooks them in a large ceramic pot. This is a stewed dish that cooks for about 5 or 6 hours with daikon (radish) and konnyaku (yam starch). Even Japanese folks are not often familiar with this dish, it is not served throughout Japan too often, but my Father-In-Law is from Kagoshima and they have cooked it for me as they know how much I like ribs.
My wife makes her own miso, it takes about 6 months to ferment.