Put the strawberries without stems and sugar into a pot.
Mix them briefly, and turn on the heat to low.
The water comes out from the strawberries as soon as start cooking over low heat.
This much water comes out in about 5 minutes without adding any water.
Add the thin round lemon slices, and simmer some more over low heat while skimming off the scum.
It's boiling down gradually. It looks like this in 10 minutes after starting simmering.
It looks like this in 20 minutes after starting simmering. Adjust the consistency by the simmering time. When it's cooled, it becomes a little bit thicker.
Remove the lemon slices. When cooled, transfer to a container or a bottle to keep.
Story Behind this Recipe
I usually simmer the strawberries if they are starting to go bad when I forget to eat them, or if I can't eat them all when a lot of them are given to me as gifts from several people.
The strawberries easily get burned if there is no water when you start simmering, so please be careful. If you are not in a rush, leave the strawberries for a little while after mixing with sugar. If you simmer after that, you don't need to worry, as long as you don't simmer too long since the water comes out from them.