Line a large sieve with a layer of fine-mesh cheesecloth and set it over a large bowl.In a heavy 6 quart pot, combine the milk, cream, salt and sugar and bring to a boil over medium heat, stirring occasionally to prevent scorching. Add the vinegar and reduce the heat to low. Simmer, stirring continuously, until the mixture curdles, 2-4 minutes.Pour the mixture in to the lined sieve and let drain for 1 hour.Discard the liquid in the bowl or keep the whey for another use. Transfer the ricotta to a jar, cover and refrigerate. Keeps for up to 5 days.