Heat milk in a large pot over medium-low heat, stirring frequently, until it registers between 178°F to 190°F (80°C to 90°C) on the thermometer. (see notes)
Turn of the heat and then add the yogurt. Stir for 10-15 seconds and let sit for 2 minutes.
Add half the vinegar and mix again for 10 seconds. Then let it sit for another 2 minutes.
Stir in the other half of vinegar and mix slowly for one minute.
You will notice how the milk has become a curd and has started to separate from the whey. Set aside until it reaches room temperature (about 1 hour).
Line the colander with 2 layers of cheesecloth or a clean kitchen towel and set it over a large bowl.
Transfer curds to the prepared colander, cover, and allow to drain for about 20 minutes.
When most of the whey has drained off, lift the edges of the cheesecloth up and twist, wrapping the cheese into a ball; then carefully squeeze off excess whey.
Place the cheese on a container and add salt to taste. Mix well with a wood spoon (don't over mix!).
Use molds to give it a shape or make it rounded with your hands. You can also use a bowl and place it there.
Place Queso Freso in the refrigerator and let it sit for a couple of hours before consuming it.
This recipe yields 740 gr (about 1 ½ lb) of fresh cheese.
If you do not have a thermometer, you will notice that the milk begins to make little bubbles around the edges of the pot, that would be the exact moment when you need to add yogurt and vinegar.
I’ve noticed that when I don’t let the curds cool completely, the cheese tends to get creamy, so it’s important to let it cool completely if you want a cheese that crumbles well.
If it's the first time you make the Queso Fresco recipe, you might notice that the cheese is a bit creamy (like cream cheese); this may be for several reasons. For example overmixing when seasoning with salt or pressing so hard when shaping.
You can omit the yogurt if you want, just add one more tablespoon of vinegar.
Making Queso Fresco with the exactly crumbly texture from the store-bought version takes a bit of practice. The first few times it will tend to be creamy, other times it will be a little crumbly (like cottage cheese). The important thing is the taste. So don’t get discouraged and keep trying until you’ll reach the texture you prefer.