This sorbet calls for elderflower soda, which can be found in the sparkling water aisle in most grocery stores (it's also called Elderflower Presse, so keep an eye out!).
Add the honey, water, tea bag and thyme into a saucepan over medium heat, stirring until honey has dissolved. Increase the heat and bring to a boil for a minute. Put the lid on the pot, and allow to cool (covered) until it's room temperature.
Meanwhile, purée the blueberries in a food processor until smooth. Press through a fine sieve into a bowl to discard the seeds. Make sure to press the purée hard with a wooden spoon to make sure you don't miss anything.
Stir the blueberry purée into the honey syrup along with the Elderflower and lemon.
Add to a prepared ice cream maker and process according to manufacturer's directions. After about 20 minutes in the machine, gradually pour in the lightly beaten egg white.
Transfer sorbet to a shallow container and store in the freezer until ready to serve.
Recipe provided by Abbey Sharp, R.D., of Abbey's Kitchen.