Cold Brew Tonic Recipe

Combine coffee and water

In a large jar or pitcher, add 1 cup coarsely ground coffee. Pour in 4 cups cold, filtered water, ensuring all grounds are fully saturated. Stir gently for 10–15 seconds to make sure no dry pockets remain.

Steep

Cover the jar or pitcher and steep at room temperature or in the refrigerator for 12–18 hours. Longer steeping yields a stronger concentrate; 12 hours provides a balanced concentrate, 18 hours is bolder.

Strain

After steeping, strain the mixture through a fine-mesh sieve lined with cheesecloth or a coffee filter into a clean container. For a clearer concentrate, strain a second time. You should have roughly 3 to 4 cups of cold-brew concentrate. Transfer to the refrigerator until cold.

Prepare glass

Fill a highball or Collins glass with 1 cup ice (or to the desired level).

Add simple syrup (optional)

If you prefer a slightly sweeter drink, add 1 teaspoon simple syrup to the glass over the ice. This step is optional; tonic water is already slightly sweet and bitter.

Pour tonic and cold brew

Measure 8 oz chilled tonic water and pour it gently into the glass over the ice. Then add 2 oz cold-brew concentrate. Pouring tonic first, then cold brew preserves the tonic's carbonation and creates a layered visual effect.

Citrus finish

Squeeze the juice of half the fresh lime or lemon into the drink (about 1/2 the whole fruit). Drop the squeezed half into the glass if you like more citrus aroma. Stir gently once to combine without losing too much fizz.

Garnish and serve

Garnish with a lime wheel or twist to taste. Serve immediately. Adjust strength by varying cold-brew: use 1–3 oz to taste; adjust sweetness with additional simple syrup if desired.