Just make cold brew! It's called "cold brew", but you can still make good hot coffee out of it.
Cold brew is essentially hyperconcentrated, but slow-brewed, coffee. It's very popular in the United States in the summer, because it's very easy to make excellent iced coffee with a cold brew concentrate. (Just add water and ice.) But you can also make a cup of hot coffee out of cold brew concentrate: just add hot water instead of cold water and ice.
Here's a recipe, but I'll summarize it.
- ~12 oz coarsely ground coffee
- ~6 cups water
Pour water over coffee in a large bowl or pitcher and stir. Cover with a tea towel and let sit on the counter (or fridge) for 24 hours. You can vary the coffee:water ratio and brewing time depending on your preferences. Strain thoroughly. Reserve the delicious liquid and discard the grounds. The concentrate will keep in the refrigerator for up to a week.
To make a cup of hot coffee, add about 2 parts hot water to 1 part cold brew (depending on your taste). Add the hot water slowly until it's tasty to you. Dilute with a similar amount of cold water for iced coffee - then add ice. Add milk, sugar, and other fixings as desired. (If you're drinking it iced, you'll want to use simple syrup to sweeten, since plain sugar won't dissolve well in cold liquid.)