Combine all of the ingredients in the Instant Pot. Secure the lid, and set the pressure release to SEALING. Select MANUAL, and pressure cook on HIGH for 5 minutes. Allow to NATURAL RELEASE for up to 25 minutes (or QUICK RELEASE after 15 minutes, for slightly weaker tonic). Strain, and transfer to glass jars. Serve warm, sweetened with a bit more honey or maple syrup if needed ;). It's best hot.
For reference, this is the Instant Pot I used for this recipe: Instant Pot DUO Plus 6 Qt 9-in-1