turn on the dehumidifier or the exhaust fan
collect fresh birch sap
strain birch sap
heat the sap to boiling in a dutch oven OR an instant pot on sauté, refer to the directions for either method in the post itself, although it is generally the same method
preheat the crock pot on high if using
for the IP: once sap is just about to boil reduce the heat in the instant pot to high on the slow cooker mode and cook for 10-12 hours or longer as needed
for the slow cooker: pour the almost boiling sap into the slow cooker, put the lid on, cook it at high and turn the lid to the side so the water can escape cook for 10-12 hours or longer as needed
as it cooks down it will get thicker and thicker, keep checking it, your slow cooker or instant pot will be different than mine so this is where you come in a monitor it, if after 10-12 hours it's still watery keep on cooking being sure to vent it so the water can cook out
you can cook this overnight if needed, in fact it might be better to cook it low and slow overnight and finish it in the morning
once it's thick and very reduced to about 1/2 cup, it is done, remove it from the heat and put it in a jar
store in the fridge, use within two weeks