Wash the strawberry tree berries thoroughly. Add the fruits to a pot or pan, and cover  with 110ml (½ cup) of water. Bring them to a simmer. Break the fruits down using a spatula. Add the sugar and lemon Juice, and cook the jam for about 20 minutes.

Next, pass the jam through a sieve.

Do a wrinkle test to check if the jam is ready. Add a small amount onto a cold plate and allow it to cool. If the jam wrinkles when you push it with your finger, it is ready.

Heat the jam again before filling it into your sterilized jars. Reserve about 1.5 cm (¾ inch) of space in  the jars. Seal them, and place them in boiling water for 10 minutes. Carefully take them out of the hot water, and let them cool to room temperature.