Classic Set Vanilla Skim Milk Yogurt

Steps

1. Wash a heavy pot, whisk, thermometer, 4 jars and lids in hot soapy water, then rinse with boiling water to sanitize and let air-dry.
2. Set the plain yogurt starter on the counter so it loses its chill while the milk heats.
3. Pour the commercially pasteurized skim milk into the pot and heat over medium-low, stirring often so it doesn't scorch, until it reaches 180°F (82°C).
4. Hold the skim milk at 180–185°F (82–85°C) for 15 minutes, stirring now and then; this firms the set for a classic spoonable texture.
5. Take the pot off the heat and cool the milk to 108–112°F (42–44°C); set the pot in a sink of cold water and stir to speed this up.
6. In a small bowl, whisk the plain yogurt starter with a ladle of the warm milk until smooth, then stir this mixture back into the pot.
7. Pour the inoculated milk into the jars and cover. Do not stir again, so the yogurt sets firm.
8. Incubate the jars at 108–112°F (42–44°C) for 6–8 hours, such as in an oven with only the light on or a cooler with warm water, checking with the thermometer, until the yogurt is set and jiggles as one mass when tilted.
9. Move the jars straight to the refrigerator at 40°F (4°C) or below and chill at least 3 hours to firm up.
10. In a small bowl, stir together the honey and vanilla to make the vanilla syrup.
11. Just before serving, drizzle a quarter of the vanilla syrup over each jar of chilled yogurt; swirl it gently or leave it on top to keep the set intact. Makes about 1 kg, or 4 servings of about 250 g; keep refrigerated up to 2 weeks and save 2 tablespoons plain as your next starter.