Put the sassafras and burdock roots, coriander seeds, star anise and clove in a heavy-bottomed 2 quart saucepan that has a tight fitting lid. Pour the water over the top of the roots and spices and bring to a boil over high heat. Drop the heat to low and simmer for 15 minutes. If it keeps bubbling up and out, vent the lid just a bit.Add the molasses, stir, replace the lid, and return to a simmer for 5 minutes. Remove the pan from the heat, add the wintergreen flavouring or extract, replace the lid and let the mixture cool to room temperature. (I let mine cool on a cold burner on the stove overnight because I prepared my sassafras infusion late at night.)Line a fine mesh strainer with cheesecloth, place over a large measuring cup with a pouring spout or a pitcher, and pour the cooled infusion into it to strain. Do not press on the contents, but let the roots rest in the strainer for about 30 minutes before proceeding. While that strains, rinse the pot in which you infused it to get any lingering bits of root or spice out of it.Measure your sassafras infusion, return it to the rinsed pot and add an equal amount of sugar -by volume- to the pot. For instance, if you have 4 1/2 cups of infusion, add 4 1/2 cups of sugar. Bring the mixture to a boil, drop the heat to low and let simmer for 5 minutes. Pour the syrup into canning jars, fix clean, new, two-piece lids on top and store in the refrigerator up to a year.!To Make a Root Beer Drink from the Syrup:Use 1 tablespoon of syrup over ice to 1 cup of plain seltzer water. Stir gently. Enjoy!