Ingredients:

  • 2 lbs (900g) fresh or frozen mulberries, rinsed and stemmed
  • ½ cup (120ml) freshly squeezed lemon juice
  • 1 tbsp (6g) lemon zest, finely grated
  • 4 cups (800g) granulated sugar

Instructions:

  1. Combine the mulberries, lemon juice, and lemon zest in a large non-reactive pot. Use a potato masher to gently crush a handful of the berries to release their juices, leaving the rest whole.
  2. Stir in the granulated sugar over medium heat. Stir constantly until the sugar completely dissolves and the liquid becomes clear.
  3. Increase heat to a rolling boil, stirring frequently to prevent the bottom from scorching.
  4. After about 20 minutes of boiling, perform the plate test: drop a small spoonful of jam onto a frozen plate, wait 30 seconds, and push it with your finger. If it wrinkles, it has reached the setting point; otherwise, boil for another 2–3 minutes and test again.
  5. Remove from heat and skim off any white foam from the surface. Pour the hot jam into sterilized jars, leaving ¼ inch (6mm) of headspace, seal tightly, and let cool undisturbed for 24 hours.