Step 1

Blend ginger, turmeric, honey, lime juice, black peppercorns, and 3 cups water in a blender until smooth. Strain through a fine-mesh sieve into a large bowl. Stir in chia seeds and let sit until seeds begin to swell, 8–10 minutes.

Step 2

Divide tonic among ice-filled glasses. Top off with club soda and garnish with thyme sprigs, if desired.

Step 3

Do Ahead: Tonic can be made 1 day ahead. Cover and chill. Stir vigorously before topping off with club soda.