Cold Brew Tonic Recipe

Combine coffee and water

In a clean jar or pitcher, add 0.75 cups coarsely ground coffee. Pour 3 cups cold filtered water over the grounds, ensuring all grounds are saturated. Stir gently for 10–20 seconds to fully incorporate.

Steep

Cover the jar or pitcher and let steep at room temperature or in the refrigerator for 12–18 hours. (12 hours yields a lighter concentrate; 18 hours yields a stronger, more concentrated cold brew.)

Filter

After steeping, strain the coffee through a fine-mesh sieve lined with cheesecloth, a coffee filter, or a nut-milk bag into a clean container. If desired, filter a second time to remove fine sediment. The resulting liquid is cold brew concentrate; if very strong, you may dilute slightly with water before serving.

Chill

Place the filtered cold brew concentrate in the refrigerator until fully chilled (if not already chilled).

Prepare glass: Fill a 16 oz serving glass with 1 cup of ice cubes.

Measure tonic: Pour 8 oz of well-chilled tonic water into the glass over the ice.

Add cold brew: Gently pour 4 oz of cold brew concentrate over the tonic. Pour slowly over the back of a spoon or down the side of the glass to create a layered effervescence if desired. If your cold brew concentrate is extremely strong, dilute to taste with up to 1–2 oz cold filtered water before adding.

Sweeten (optional): If you prefer a sweeter drink, add 0.5 tablespoon simple syrup and stir gently to combine. Start with less and add more to taste.

Garnish and serve: Express a citrus peel over the drink to release oils, then drop the peel or add a thin slice to the glass. Serve immediately with a straw or stirrer.