squeak- thanks for your comments. I am pretty sure you just cannot make coffee with cold water- in other words, putting the ground coffee in cold water. try it- it tastes terrible, even if heated . somehow, chemically, the ground coffee must come into contact with hot water- NOT boiled water. Any of the usual methods-drip,french(with a plunger), even turkish coffee, all of them deal with hot water. If you google coffee making, I am pretty sure it will tell you all about it.
As far as the difference of “afyiah’ and ‘zli”, I always associated ‘zli’ with frying in oil-a liquidp- whereas ‘afyah’ is without any liquid. Roasting coffee beans happen without liquid. In any case, it makes very little difference in halacha, as there is ‘bishul achar afyian’ and “bishul achar zli”. Incidentally, i daresay, yo ucna oast coffee beans in an oven and you will nto be able to ‘fry” it in oil.