Pour the milk into a medium pot. Place on medium-high heat and, when it comes to a boil, turn the heat off and add the vinegar. Stir as the milk starts to curdle. Line a large sieve with cheesecloth and, holding it over the sink, pour the milk curds into it, letting the whey drain into the sink. Place the sieve over a bowl and fold the ends of the cheesecloth over the cheese. Set weights on top to press out excess liquid and refrigerate for several hours or overnight, until it's solid.