In a small saucepan, combine the water and herbs. Cover and bring to a boil over medium heat. Once boiling, reduce heat to a simmer and let simmer for 10 minutes.
Remove from the heat and let steep for another 30-60 minutes.
Strain the infusion over a glass measuring cup so you know how much have. You should have around 1 cup of infusion. Rinse the saucepan, then pour the infusion back into the pan. Measure out an equal amount of brown sugar and add it to the pan.
Heat the mixture over low heat, stirring occasionally, until the sugar has fully dissolved. Remove from heat and let cool to room temperature.
Store the syrup in an airtight container (a glass jar works well) in the fridge for 2-3 weeks.