Step 2: Oven time
I let them cook at that heat for about 45 minutes. Then I turn the oven on to about 200 and wait a few hours. This juices them up, or something. It's a slow wet roast, actually, and it makes them really soft.
When you turn the oven down, also cut a small steam vent in the top of the foil, or remove the cover partially. This will keep the ribs from getting soggy- the idea is to steam them so that the meat is juicy and tender, but not to soak them. Once the heat gets turned down they will be slow-cooking in their own fat and juices, not in the water. If you've cut a vent, leave them for about three hours. If you've removed the cover completely, give them about an hour and a half.
If you want to add some onion powder you can put that in now too. I think it tastes good.