I'm a newbie in coffee knowledge who recently started taking black coffee daily. I heard medium grind size is good for cold brew (Hario Mizudashi) or french press, but my father recently sent me 2kg of coarse grind coffee from various local beans (I'm from Indonesia).
I used to brew medium-fine Flores bean and the fine M&S Espresso No 5 for both french press and cold brew (for 12 hrs). The first coarse-grind beans I tried was Sidikalang. Using Mizudashi, I didn't weigh the beans but using the same measure as the medium-fine, around 3/4 size of Mizudashi filter. After 12 hrs, the coffee tasted very weak. It's bitter but lack of taste which I didn't expect, based on the characteristic I read. I haven't tried the other beans as I wanted to finish this one first.
I wonder if it's because of the wrong grind size, the amount, or the brewing time. Should I brew it longer? Otherwise, what is the brewing method usually good for the coarse grind size?
All opinions will be greatly appreciated.