Cold brew. You can have it in 12 hours if you leave it on your counter or 24 hours if you soak it in your fridge.
Add grounds, add water, steep, strain twice, add water, enjoy.
Not bitter or acidic, doesn’t need sugar or milk (unless you prefer).
Drink it hot (add hot water to the concentrate) or cold.
Here’s some info on the latest fad that is cold brewed coffee.
Epicurious gives a fancy overview of cold brew.
The New York Times easiest instructions ever.
Expert reviews on the best pre-made brands.