Why doesn’t this exist?
Take dried beans, roast 'em, grind 'em, and brew some bean juice?
I have no idea if it would taste good or not, but we don’t know if we don’t try.
Edit: I need to see what dried beans I have and maybe go shopping. I will give this a try with a couple different types of beans and report back if I fart or not.
I drank it in Taiwan among other very low sugar juices that I prefer over plain water. It’s just one of many drinks made from ingredients we never thought of, like mushroom drinks and cereal grain drinks. The bean drink must have been forgettable enough that I can’t describe the taste after four years away.
https://www.agv.com.tw/product-category/beverages/
Just wanted to add that tea with black beans, red beans, roasted barley, roasted rice etc are common in Japan. I assume Taiwan has the same, judging from the drinks posted above (the label even says the Japanese name in roman letters).
Barley tea is delicious.