You will need some unusual ingredients to make this, notably sassafras roots. If you happen to live in the United States or Canada east of the Great Plains, you are in luck: Sassafras grows everywhere in that region. If you don’t live there, or don’t feel like foraging for your own sassafras, you can buy sassafras root bark online. The burdock in the recipe grows all around you as a weed. Otherwise, many good supermarkets have burdock in the produce section: They are long pale, skinny roots often sold under their Japanese name “gobo.” If you absolutely cannot get your hands on burdock, use dandelion roots. The root beer will be different, but still fine.
Chop the sassafras and burdock roots into small pieces, about 1/2 inch or smaller.
Put the roots in a medium-sized heavy pot with the clove, star anise and coriander seeds and cover with the water. Cover the pot and bring it to a boil. Simmer this for 15 minutes.
Add the molasses and simmer another 5 minutes.
Turn off the heat and add the wintergreen or peppermint extract. Put the cover back on the tea.
When the mixture cools, strain it though cheesecloth to remove any debris.
Return it to the pot with an equal amount of sugar. Stir to combine. Bring it to a simmer and cook it for 5 minutes, uncovered. Pour into quart mason jars and seal. Keeps a year in the fridge.
Notes
If you can find it, get wintergreen extract. If not, use peppermint extract.