Plum juice or ume juice making can only take place in the plum season which is early June.
I usually make plum juice instead of ume shu (alcohol) so that children can enjoy it, too.
Here is the receipt.
・1kg Ao Ume (green plums, not ripened plums) I bought them from Sakuraya.
・1kg Rock Sugar I bought them from Fairprice.
・3ℓ glass container I bought them from Japan Home.
How to make
1. Wash plums gently with water
2. Remove stem ends
3. Wipe off water from plums
Use kitchen paper to wipe off moisture, then let sit for 1 hour so they are completely dry.
*Option: You can poke plums using a fork so that juice may come out faster. (My grandma always did this)
4. Sterilize containers to avoid mold growth
5. Place plums and rock sugar in the container
Repeat the layers.
6. Leave them for about 2 weeks
Turn the bottle to mix the juice with plums at least once a day
*I am doing my experiment here. Right: without poking, Left: with poking, trying to find out some difference in taste.
It looks like the left one (poking) produces juice faster.