Grind your coffee beans coarsely. I recommend a level of 9-10 out of 10.

Place them in the bottom of the mason jar.

Pour half (1 1/2 cups) of the water over the coffee grounds, stir and wait a minute.

Pour in the rest of the water.

Put on the lid and place in the fridge for 12-18 hours. I recommend trying it at 12 hours. If it's not strong enough, let it sit a few more hours. I personally think 16 hours is best.

Put a rinsed paper coffee filter or a cheesecloth in a fine-mesh sieve. Place the prepared sieve over a bowl (I recommend one with a pouring lip/spout for easy pouring).

Pour over the coffee. Rinse out the mason jar and pour the strained coffee back into the mason jar.

Cover and refrigerate for up to 7-10 days.

To serve, dilute it 1:1. So measure out 1/2 cup cold brew concentrate and add 1/2 cup of water or milk.