Brew coffee using your preferred method (drip, pour-over, French press), but use twice the amount of coffee you normally would for the same amount of water.
Immediately pour the hot coffee into a pitcher filled with ice to "flash chill" it, preventing oxidation and preserving flavor.
Alternatively, let the coffee cool to room temperature before refrigerating.
Serve over fresh ice.
Pro Tip: For the best flavor, avoid letting hot coffee sit on the counter for hours to cool. Flash chilling or rapid cooling in the fridge preserves a brighter, less stale taste.