Looks like this is done by using a crockpot/slow cooker/pressure cooker.
It seems to add up. 👇🏼

I do mine on the stove (cookpot with glass lid) and have used this for at many years now. Works great! Haven't had a cold, flu, etc, since before the plandemic started. After making it, I freeze it in smaller sizes that hold a couple doses and thaw/take some if I feel any symptoms. Don't take the lid off till it completely cools; make sure to soak the fruit (whole) in some vinegar water first, to take off any of that wax that they sometimes put on fruit to preserve it while shipping.