Related:

My actual procedure I followed?

For 500g setting sugar, and a bit more than that of strawberries

  • Preheat oven to 180C
  • Wash strawberries with damp towel (prevents water absorption)
  • Cut strawberries into pieces, mash lightly, mix with sugar, leave to sit at room temp (12hr or overnight recommended but nah)
  • Wash jars with warm soapy water and dry with tea towel
  • Prep pan with water, warm up to simmer, turn off heat
  • Place saucers in fridge? Freezer?
  • Place strawberries and sugar in pot with juice of half a lemon
  • Low heat until sugar is fully dissolved
  • While waiting, place jars in oven and lids in boiling pan
  • Once sugar is dissolved, boil for 5-10min, turn off heat, and test on back of cold saucer. If not set enough, then turn heat back on and boil for 2min at a time, turn off, test again
  • Meanwhile, take jars and lids out after 10min, place on clean towels
  • Spoon scum off top of jam
  • Add small knob of butter
  • Spoon jam into jar whilst both jam and jar are warm
  • Leave to cool