Do not use UHT milk. Regular pasteurised milk is fine.
You can work 1 teaspoon of salt into the mixture if desired; simply knead in the salt while stretching the curds in step 8.
If you want a softer textured, moist mozzarella, do not let the curd set as firm and work less when stretching and kneading.
You can create any shape you desire - try larger balls, small balls, or twists and knots.
At the end of step 7, you may place your curds in a plastic bag and store both the curds and the whey in the fridge for 2 to 3 days before continuing the process.
This is the best of the mozzarella recipes I have found and tried,and had a fair amount of success with it. Practice makes perfect. I would recomend giving it a go. - 08 Jan 2013
@NadiaE, are you using Ultra-Pasteurized milk? Ultra high heat alters the casein and makes it unsuitable for cheese. - 20 Jul 2016
So disappointed! Have tried making mozzarella 3 times, following the exact recipe but keeps crumbling and falling apart at the stretching stage. Tried full fat milk from 3 different stores, using thermometer, measuring precisely. What am I doing wrong?? Determined to make this work so any advice appreciated! Thanks xx - 25 Feb 2016