Wash, drain and hull the strawberries. Cut them into small pieces.
Place a saucer in your fridge.
Take your largest pot and throw the strawberries in. Stir vigorously for 5 minutes (medium heat). At this stage the strawberries should be mushy.
Add sugar and juice of 1 ½ lemon. Cook until the jam has thickened (30-35 minutes), stirring regularly (better more often than less – don’t leave the pot unattended).
Take the saucer out from the fridge. Spoon some jam onto it. Let it cool down before checking for its thickness by making a line through the jam (use your finger). If the jam fills the space (the drawn line) then you need to cook it longer. If it doesn’t, you are ready to fill your jars.
Pour/spoon it into sterilized jars leaving about 1 cm/0.4 inch free from the top. Seal with lids and turn up-side down. Let it set for 30 minutes.
Half hour later: turn the jars back and check the lids to see if they are properly sealed. If you tap/push down the lid, it shouldn’t pop up and down. If it does, it is not air-tight. If this happens to you, simply put the jars in your fridge and eat within a week. The rest of the jars will last for a few more weeks (if you don’t eat them earlier, that is).