Prep: Take milk out of the fridge to come up to room temperature. Sterilize all of your equipment. Then set up a large pot or bowl with a cheesecloth-lined colander and set aside. Mix the citric acid with 1/4 cup of water in a small bowl or Pyrex. Prepare the rennet by adding it to 1 cup water. Set aside both. Heat Milk: Add milk and the citric acid with water to the pot, stir, and heat over medium until the temperature reaches 90 degrees.
Add Rennet: Remove the pot from the heat and then add the rennet and water and give a gentle mix. Cover the pot and let sit for 5 minutes.
Curds: After 5 minutes, soft curds should form. With a long spatula or knife, cut the curds into 1 inch squares.
Return to Heat: Turn the burner to medium and return the pot to reheat. Gently stir until the whey is 105 degrees. Remove from heat.
Scoop Curds: Using a slotted spoon, gently scoop the curds from pot into the cheesecloth. Repeat with all curds. We don't recommend pouring all of the whey into the cheesecloth, just because it will take too much time to drain all of that liquid, and it likely won't fit into your cheesecloth. Just do your best to scoop as much as you can out. Drain: Gently gather the ends of the cheesecloth and gently squeeze out some of the liquid.
Heat Curds: Transfer cheese to a medium-sized microwave-safe bowl. Heat in the microwave for 30-60 seconds to heat the curds to about 135 degrees, but be careful to not heat it too much as if the temp goes over 170 degrees, the curds will fall apart. See recipe notes about how long to microwave, based upon the strength of your microwave.
Release Whey: Using food-grade gloves, gently press down on the microwaved cheese to release whey and then drain the whey from the bowl. Drain whey, and
Repeat: Return the bowl to the microwave and heat again for another 30 seconds, release and drain whey, and then heat for a final 30 seconds and do one final drain of the whey.
Salt and Stretch: Sprinkle the cheese with 1/2 teaspoon of salt and gently knead cheese. Sprinkle with another 1/2 teaspoon and use your hands to begin to stretch the cheese a couple of times.
Form and Chill: Form the cheese into a ball and chill immediately in a bowl of ice water to cool for 5 minutes.
Slice and serve!