To begin, prepare the citric acid and rennet. Stir the citric acid into a bowl filled with approx. 240ml water until dissolved. Dissolve the rennet in 60ml water in a separate bowl.

Pour the milk into a large saucepan and stir in the dissolved citric acid solution. Warm the milk over medium heat, stirring gently, until the temperature reaches 32C/90F.

Remove the pan from the heat and gently stir in the dissolved rennet solution for 30 seconds. Use the spoon to break the current so the milk is still, then place a lid on the pan and leave for 15 minutes, undisturbed.

After 15 minutes, the milk should have set. If not, recover for another 5 minutes or so.

Once set, use a long knife or offset spatula to cut parallel horizontal and vertical lines in the cheese, ultimately cutting the cheese so the top of the pan resembles a grid. Make sure your knife goes all the way to the bottom of the pan.

Set the pan over medium heat and warm the contents to 41C/105F, stirring very gently to avoid breaking the curds too much.

Remove the curds from the heat once up to temperature and continue to stir gently for a few minutes.

Gently strain the curds into a microwaveable bowl, reserving the whey (liquid), which can be used for various other recipes.

If using the microwave method, microwave the curds for a minute and drain off the whey. Fold the curds on themselves, optionally wearing rubber gloves. The cheese curds will still be very loose at this point. Return to the microwave for 30 seconds. Test the internal temperature of the curds, which should read 57C/135F. If not hot enough, continue to microwave in 30 second increments, checking the temperature each time.

If not using a microwave (skip this step otherwise), warm a large pot of water to around 87C/190F. Pour the curds into a sieve and nestle in the pan so the curds are submerged in the hot water. Let sit for a few minutes then fold the curds under the water (bearing in mind that the water will be very hot). Leave to sit for 5 minutes. Fold again and check the temperature (which should reach 57C/135F). If not hot enough, leave to sit for longer.

Once hot enough (having used either the microwave or hot water), continue stretching the curds and sprinkle over the salt. Rub into the cheese and continue to stretch and shape using both hands. Once firm and glossy, form the mozzarella into one large ball or multiple smaller balls.

Cool and eat straight away or store for up to a week in the fridge, in a container submerged with leftover way and another teaspoon of salt.