Heat 1 liter of milk to 85–90°C
Cool the milk to 40–45°C
Mix in 2–3 tablespoons of plain yogurt with live cultures
Stir gently until fully combined
Cover the container
Keep it warm for 6–12 hours
Check that the yogurt has set
Refrigerate for at least 4 hours
Line a strainer with cheesecloth or a clean cloth
Pour the yogurt into the strainer
Let it drain in the refrigerator for 2–8 hours
Collect the thick yogurt left in the cloth
Transfer the Greek yogurt to a clean container
Store in the refrigerator and use within 5–7 days