Place several layers of cheesecloth over a fine-mesh strainer, then nest the strainer over a mixing bowl.
Pour the milk into a 2-quart pot over medium high heat and affix a thermometer to the side of the pot. Heat the milk, stirring occasionally to prevent scalding, until the temperature reaches 175-180°F, 7-8 minutes.
Turn off the heat, but leave the pot on the warm burner. Add the salt and white vinegar to the milk. Stir gently until curds form and completely separate from the whey, 1-2 minutes.
Allow the curds to sit in the warm whey (this is called "holding" the curds) for 10-20 minutes. Keep an eye on the temperature - if it dips below 170°F, turn the burner to a low flame and gently reheat the milk to maintain a temperature in the range of 170°-180°F.
Use a wide slotted spoon to scoop the largest curds from the whey and transfer to the cheesecloth. Then gently pour the remaining mixture through the cheesecloth.
Allow the ricotta to drain naturally for 5-30 minutes, depending on your preference for consistency (see notes). The liquid that drains from the cheese mixture is called "whey" and will collect in the mixing bowl.
Scrape the ricotta from the cheesecloth into a bowl, taste for seasoning, and sprinkle in extra salt as desired. If the ricotta is too thick, stir in additional whey, a teaspoon at a time, until the desired consistency is reached.
Serve warm immediately, or transfer to a lidded container and store in the fridge for up to 5 days. Makes about one cup.
Notes
Do not use ultra-pasteurized milk, as it will not curdle.
Notes on temperature:The trick to getting ricotta just right is heating the milk to the right temperature. Too hot and you'll end up with harder curds better suited to a paneer-type cheese. Too cool and your curdles will be too soft or small. Aim for 175-180°F and use a digital thermometer for accuracy.Notes on consistency:
Wetter ricotta is great for serving on its own with a bit of honey and berries as dessert.
A medium consistency is great for spreading on toast or flatbread
A drier consistency is suitable for traditional, store-bought ricotta uses, like lasagne.