Add the raspberries and sugar into a medium size saucepan.
Crush it up with a wooden spoon and cook the crushed raspberries on medium heat for about 15 to 20 minutes.
Then add the lemon juice.
Pour the cooked raspberry and sugar mixture through a fine-mesh sieve into a bowl and let it cool completely before transferring to a jar to refrigerate. Tip: Use a spatula to mix and press as much of the mixture through the sieve as possible. Keep refrigerated in an air-tight jar for about one week.