In a small bowl, combine pectin with ¼ cup sugar; stir to mix. In a large pot, add strawberries and zest; sprinkle pectin mixture. Set the heat to medium-high, stirring often.
When strawberries start getting soft, using a potato masher, crush them to desired consistency (release natural pectin); cook for 10 minutes. Add remaining sugar, stir well, reduce heat to medium and bring it back to a full boil, skimming the foam on top; cook 5 minutes.
To know if it’s ready with a desired consistency; dip a metal tablespoon in ice water for a few minutes. Dry it off and scoop some strawberry jam. Let it cool at room temperature and if sets up, it’s ready. Process with canning procedure. Makes 6 jars of 250ml.