TheKitchn.com homemade mozzarella recipe combines simple ingredients with exacting techniques. Begin the process by choosing any kind of milk except ultra-high temperature pasteurized milk, which prevents the proteins from setting curds.
Mix 1 cup of water with 1 1/2 teaspoon of citric acid, and stir until dissolved. In a separate dish, dissolve 1/4 rennet tablet or 1/4 teaspoon of liquid rennet in 1/4 cup of water.
Pour 1 gallon of milk and citric acid water into a 5-quart nonreactive pot, such as enamel or stainless steel, and stir. On medium-high heat, warm the milk mixture to 90 F while gently stirring. Remove from the heat, and add the rennet water. Slowly stir while counting to 30. Cover the pot, and let it sit for five minutes, undisturbed, to let the milk set into curds.
Cut the curds in a checkerboard pattern, making sure to cut all the way through. Return the pot to medium-high heat, and warm to 105 F while slowly stirring. Remove the pot from the heat, and continue stirring for five minutes. Using a slotted spoon, place the curds in a microwave-safe bowl. Microwave for one minute, and then drain the whey. Fold the curds over onto themselves a couple of times.
Continue alternating between cooking for 30 seconds and folding the curds, until the internal temperature reaches 135 F. Sprinkle the cheese with salt, and incorporate it by squeezing between fingers. Use both hands to pull and fold the cheese until it begins to firm up and becomes glossy. Shape into balls and use immediately, or cover in cool whey and refrigerate.