Smash down the berries with a potato masher. Measure the amount of berries so you know the amount of sugar you will need. For every one cup of smashed berries, use 3/4 cup sugar. Add the sugar and lemon juice. If you would like to remove the seeds, this is the time to do it by pressing the mixture through a sieve.

Cook over medium heat until mixture starts to simmer. Simmer by half or until it has properly thickened. Keep in mind it will thicken more as it cools.