Start by sanitizing your jar.
15 minutes at 190F (88C) in steam mode is more than enough.
Pour the milk into your sanitized jar.
Sanitize your Combi oven's probe.
Turn the combi oven to 250F (121C) in combi mode and probe the milk.
Heat the milk until it is 175F (79C).
Chill the milk until it is 115F (46C). We used an Alto-Shaam quick chiller but you can just leave it on the counter if you don't have a chiller. It will just take longer.
When the milk is cooled to 115F (46C), You are ready to add the yogurt with live culture.
For 1/2 gallon of milk we added about 3 ounces of yogurt. It is very important that your yogurt has live culture. This is what makes the milk into yogurt.
Place the milk mixed with yogurt into your cooking hold oven at 115F (46C) For a minimum of 6 to 8 hours. You can even leave it in overnight if you want to for a tangier flavor.
Remove from the 115F (46C) cabinet.
You will see that some water has separated out. This is ok.
Refrigerate the yogurt.