Cold Infusions
A few herbs, such as sweet violet and marshmallow, have beneficial compounds that are best infused in cold water, rather than hot. In this case, you can soak the herb in cold water in your fridge overnight, then gently heat in a saucepan, but not quite hot enough for a simmer. Heat uncovered for about 15 to 30 minutes, then turn off the burner. Cover the pot and let the herb/leaves steep for another 20 minutes or so. Strain and make your syrup.