What's the best way to reheat coffee?
Is there one?
Of course coffee is best enjoyed freshly brewed, but what do you do (if anything) to freshen up a cup of coffee if it's been left to sit around a bit too long?
I find that I can rehabilitate a ceramic mug o' joe with a couple of minutes in the nucleator, being careful to avoid bringing to a boil. Since I take my coffee black, no sugar (as the good Lord clearly intended) no worries about long-chain milk proteins turning to muck.
I nuke cold coffee on high for 1 minute per cupful.
I usually pour the just brewed coffee into a insulated carafe that I can pour from all day at the perfect temperature.
Since I still make mine in a Chemex pot, I adhere to the process I was taught shortly after we invented fire: put the pot into a pan it'll fit easily, then fill the pan with water just to the coffee level. Put this on the stove and bring just to a gentle boil. The coffee will not taste perfectly fresh, but will have less of an off-taste than you get from any other method. Microwaving is next-best.