Cut guava into large chunks. Fill the pot with little water and place guava in it.
Cover the lid and boil guava for 10-15 minutes on medium heat until soft.
Remove from heat and blend with an immersion blender. Just a few pulses, do not blend seeds.
Strain to get puree and discard the seeds.
Guava Jam
Take Guava puree, sugar, lemon juices, and spices (if using) in the thick-bottomed pot.
Cook jam for about 30 minutes on medium heat with occasional stirring. Once the jam starts to thicken stir frequently. (Vigilant observation will be necessary as the jam reaches the setting point.)
The jam is ready when you see the bottom of the pot clearly while stirring. Another tip is when you draw a line on the spatula, the jam will coat the spatula thickly. (Do not overcook or the sugar might caramelize and burn to make the jam bitter.)
Remove cinnamon sticks and cardamom pods from the jam.
Transfer hot jam plum jam to clean and preferably sterilized jars. Seal the lid and turn the jars upside down.
Store in the fridge if consuming immediately. Or follow proper sterilization steps and seal it for canning and follow the water bath procedure if intending to store it in the pantry for a longer period. Or let the jam cool completely for 12 hours then freeze.
Video
Notes
Guava: Use best tasting, smooth, fully ripened guavas for jams that are not grainy.Sugar: Use at least 1.5 cups sugar for 1 kg (2.2 guavas) for a low sugar jam. You can add up to 4 cups of sugar if you like it very sweet.Storage:Homemade guava jam lasts for 6-8 weeks or more in the fridge without preservatives. Use a clean spoon to serve each time. If you freeze jam, they can last up to 6 months or more. If you intend to seal and store jam at room temperature in the pantry. Then proper canning steps of hot water bath and store jam in the fridge after opening.More quick methods to make Puree:
If your guava center is soft and has many seeds then you can just scoop out the seeds with a spoon. Blend the pulp with 1 cup of water to get seedless guava puree. Proceed with jam-making steps.
If your guava is firm with a solid center, full of seeds. You can't scoop seeds from hard fruit so boil guava until soft then scoops the seed and discard. Blend the pulp with 1 cup of water. Proceed with jam-making steps.