'Chaga - The Facts' Article
The following link is a wonderful resource about the Chaga Mushoom; its history, current use, bioactive ingredients, and includes references.
Chaga – The Facts (article from Oriveda)
Making Chaga Mushroom Tea
Note: Chaga is a powerful and important living organism in the boreal forest. It plays a very crucial role in the health of the birch trees and others. We should seek to only buy chaga that has been sustainably harvested (in other words the harvesters are not simply harvesting as much as they can find from a location - but only selectively harvesting the larger conks and leaving others in a region to continue to spread and propagate the chaga). It is also important that we only use as much as we need to make a good strong tea. Chaga is becoming very popular in the natural health marketplace and may over time become endangered. Not only are we concerned about the healthy survival of the chaga but also the role it plays where it is living.
Chaga has been prepared as a tea, decoction, extract, syrup injection, suppository, tablet and aerosol (Hartwell 1971).
Prepare a tea by boiling the ingredients for a few minutes and then letting it sit on a low heat for about 1-2 hours. You can drink some right away after it boils but it is better to let it sit for a while to become stronger. Use approximately 3 square centimetres or one tablespoon of crushed mushroom. It will produce 2.5 - 3 liters of tea to be to be taken in a dose of 3 cups per day, ½ hour before meals. Start out with only 1-2 cups daily for the first week to avoid detox symptoms. Continue for 15-20 weeks with intervals of 10 days of using the tea and then 3 - 7 days off of it. According to anti-tumour studies, boiling activates anti-tumour particles leading to tumour inhibition in mice (Lucas 1960). So, it seems that both folklore and laboratory evidence point toward boiling the fungus in making the tea.
You can strain it into bottles and store them in the refrigerator to drink it cold. You can use the same Chaga pieces/powder about 3 to 5 times before throwing it out. You can add a tiny pinch more of the powder or a small chunk to freshen up the pot for each new batch. Remember that we want to make the supply go as far as possible.
This recipe, from a Russian web site, contradicts the others where you are warned not to boil the Chaga. The Russian peasants that used Chaga for centuries most likely used boiling water to make their tea. So it appears that you can make the tea anyway you want and still get the benefits of the healing power of Chaga.