Pour 500 ml of water into a bowl to dissolve the citric acid.
In another, bowl add the remaining water and the rennet.
In a large thick-based saucepan, bring the milk and the citric solution to 32'C.
Stir occasionally to prevent the milk from catching on the base of the pan.
Remove the pot from the heat and stir in the rennet solution.
Cover and allow to sit for 5-10 minutes until it start to set.
After 5-10 minutes the curds should be separating and resemble silken tofu (or jelly). Run a knife though the curd in a grid pattern and put back on the heat.
Bring the liquid up to 40*C, stir gently but try not to break up the lumps too much. The curds will continue to coagulate and separate from the whey.
Remove from the heat and continue to stir gently for a further 5 minutes (and if necessary leave to rest)before skimming out with a slotted spoon into a microwaveable bowl.
Microwave for a minute, then drain off any of the remaining whey.
Begin to fold the curds gently, initially they will begin to look like cottage cheese. The aim is to stretch the curds into long, thin shreds.
Continue to alternate between stretching and kneading the curds and checking the temperature. The optimum temperature needed to create a stretchy curd is 58*C. This temperature can be maintained with short bursts in the microwave between stretching.
Sprinkle with the salt and knead in until the curds become glossy and firm.
Shape the mix into balls the desired size.
Mix a tsp of salt in with some of the whey and pour over the mozzarella balls. Keep in a air tight container.
«The mozzarella will keep in an air tight container for 3 days. In the absence of a microwave, place a large pot of water on to simmer and submerge the curds in a stariner or muslin cloth in the water, repeating the same process as above.»