Start by dissolving rennet in 1/4 cup water. Then pour milk into a large non-reactive pot. Place the thermometer in the pan and secure to the side.
Sprinkle citric acid powder over top, store the remainder for later use. Stir dissolved rennet into milk. Stir for one minute. Heat milk to 90 degrees and hold steady at that temp. This was a little more challenging with an electric cooktop than gas, but I got it to work! Do not heat over 90 degrees.
After 5-10 minutes, milk will start to separate, cheese curds from whey. Cheese curds will be a silky, gelatin-like substance. Whey is a liquidy, yellow substance, look around the edge in the picture. Using a large knife, cut curd into a checkerboard pattern with squares equaling 1×1 inches.
Continue to heat milk mixture to 110 degrees for 10 minutes. Be mindful that it does not go over 110 degrees. Cheese will continue to separate.
Line a colander with cheese cloth. Pour mixture into colander to drain. Dump cheese curds into a microwave-safe dish. Discard whey.
Microwave on high for 1 minute. Drain off the whey. Wearing plastic gloves to combat the heat, knead and stretch for 30 seconds. Heat on high for an additional 30 seconds or until it reaches 135 degrees. Curds will be really hot.
Add cheese salt. Wearing plastic gloves will prevent some of the heat from scalding your hands. As much as you can, knead the dough like you would bread. Start to pull and stretch. It might not be stretchy like silly putty, but it will still be okay. Continue to knead and stretch until it is one mass and not falling apart.
Mold into a large ball or smaller bowls and wrap in plastic wrap or submerge in ice water. Place in the refrigerator for at least 30 minutes.
Slice and serve! Enjoy your Homemade Mozzarella Cheese. Cheese will stay fresh for up to a week in the refrigerator, keep covered with salty brine water.
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