If it were me, I'd dehydrate them, then rehydrate when time to used them ( but after rehydrating, kinda squeeze out the excess moisture before sir frying).
Ive never froze them before, so Im not sure how that would work. Maybe someone has frozen them in the past and can comment on that .
I actually made a similar " oyster sauce" in the past. Obviously doesn't taste like oyster sauce, but as the site mentions, its a good way to add umami too a dish.
(Coincidentally, I literally just walked inside after picking 55 shiitake of my log, and now thinking what im going to do with all of them).
55 mushrooms, they must be starting to pay for themselves? It's so cool that you are getting more of them.
I want to hear 250 mushrooms next time.....an unrealistic dream I had.
My take on shiitake and button mushrooms:
If you buy 100 lbs of mushrooms with 85-95% water content, then you are drying them, you have more or less 10 lbs of dried mushrooms. (moisture content of powder effects that more or less) So if you wanted to buy some dried shiitakes, they might cost about
$25/lb. In fresh mushrooms that would be about 10 lbs of fresh. So if you can get fresh shiitakes at $2.50/lb or less, then go for it. Otherwise buy dried, right? (well if you want to waste money, go you! this is probably not the post for you.)
In my part of the country, mushrooms rarely go, any type, for $2.00/lb or less. So I always buy dried. Except when mushrooms are on sale. These are usually white button, usually not sliced. They are usually not washed, they are very good though. And we like button for the texture and flavor and we make mushroom lasagna.
The canned mushrooms are actually a good value. If you can them yourself they will be more expensive than buying canned (you must have cans on hand, use time and energy on yourself and your stove).
If you can put up with the salt content of canned mushrooms. You'll still have to shop and see the prices and decide, but 79 cents for 8 oz, is equivalent to a half lb of mushrooms that are cooked, so make a choice and decide for yourself. I don't know what sale prices for canned foods are for other parts of the country.
4 lbs of fresh button mushrooms unsliced and unwashed, will go on sale for $2.00/lb. When cooked down about 60 oz. Equivalent to 7.5 cans, similar price, in cans, less work for us so we buy canned. It's one of the only vegetables we buy canned, for now.
Prices change, shipping changes, economy changes, diets change, covid ... I...won't...even...go there and how it changed money for everyone.