As a first step to prepare our strawberry jam we cook the strawberries, previously washed and dried well, with the juice and grated rind of the lemon for about 10 minutes over low heat, stirring often.
Then add the sugar, mix until completely dissolved; then raise the heat and let it cook for about another 10 minutes, making sure that the jam does not stick to the bottom of the saucepan. We pour a small amount on a saucer, tilt it and if the jam sticks without releasing water, turn off the heat.
We leave everything to rest for about ten minutes. Finally, pour the strawberry jam into the sterilized jars and close everything hermetically.