Ingredients:

1 large bucket of sour starfruit chopped into fine pieces (make sure to remove tough skin and seeds)
Water (enough to fill pot with fruit in it)
Sugar (around 4 cups, may vary)
Juice of 1 lemon

Directions:

Add chopped starfruit to a pot (make sure to measure the amount of fruit in the pot by cup) and fill with water until just below fruit line.
Bring to a boil and boil until soft (this happens quickly).
Lower the heat and slowly stir in the sugar (about 1/2 cup of sugar for every 1 cup of fruit).
Add juice of one lemon and stir everything together.
Once mixture has come to a boil, bring the heat to a simmer.
When the mixture begins to gel, take off the heat.

Canning:

Boil jars, and while still hot, add in the jam.
Screw hot lid on.
Wait for the seal to pop down - if it does, it means the jam can be stored, if it does not, it means the jam needs to be used soon.

Notes:

Instead of chopping, you can blend your fruit. This will make a smoother texture, but less water will be needed.
If you prefer a sweeter jam, you can up the sugar content (about 1 cup for every 1 cup of fruit).
If the mixture doesn’t gel and taste sour, add more sugar.
Sour starfruit is recommended for this recipe, but sweet starfruit can also be used.