Turns out I can't eat 800g of strawberries by myself. So before they went gross I preserved them as delicious jam. This is be grandmas recipe.
3/4 cup of sugar (if you want it less sweet, just use less sugar)
1/4 lemon (juice) Cut and mash the strawberries. Add sugar. Boil and keep boiling until it becomes super sticky, almost caramelly. Add lemon. Jam is literally the easiest thing in the world to make, it just requires time.
As you can see, it doesn't make an awful lot. This is a pretty small jar. But it is very sugary, so you don't need a lot.