At low heat after 15-30 minutes they'll start expressing all their liquid, and after that evaporates away you're just slowly breaking the onion's content into sugars and then caramelizing those sugars until you've got a nice brown jammy thing with 1% of the volume of the original onions
o.k. so I have never caramelized onions, but after 2 hours wouldn't they just be ash?
Not if you use low enough heat and/or keep flipping and messing with them. Plus like look at how much onion is involved here.
You keep the temperature super low, the onions just kinda melt.
At low heat after 15-30 minutes they'll start expressing all their liquid, and after that evaporates away you're just slowly breaking the onion's content into sugars and then caramelizing those sugars until you've got a nice brown jammy thing with 1% of the volume of the original onions