Herbalism is an age-old traditional healing modality, as such, herbalists use many rather archaic words. Decoction is one of them.
Decoction from dictionary.com
Decoctions are usually used for rhizomes, barks, roots, dried berries, dried mushrooms, etc. Basically, the harder plant parts need to be simmered for a longer period of time in order to extract the medicinal constituents.
In general, the plant matter is brought to a boil then turned down to simmer. Depending on the plant, it may simmer anywhere between 20 minutes to 12 hours or more. More water is added as needed to prevent the pot from boiling dry.
Next, it is strained and the remaining liquid, generally 1/2 of the original liquid added, is then used to make the final product. This final product might be a syrup, gummies, candy, or some other edible form.
In the case of the ginger above, after straining, and measuring, the liquid was added back to a clean pot, an equal amount of sugar was added, then brought to a boil and to the ”soft ball” stage before being poured into a well oiled pan. This made a soft caramel-like chew to be used for nausea, sore throats, etc.
Ginger chewies 1/2c. shredded fresh ginger 2c. filtered water Decoct for 30 minutes. Strain. Measure to 1 cup of liquid. Add back to clean pot. 1c. Ginger decoction 1c. Brown sugar Using a candy thermometer, bring it to the ”soft ball” stage. Pour into well greased pan. Refrigerate. Cut into small 1/2”, square pieces and wrap individually in wax paper. Store in the refrigerator. (Modified from Vintage Remedies recipe)
If you get impatient and pour it too early, all is not lost, it can still be used by the spoonful.