Caramelized onions came out of my Dutch Oven with a bitter, (sulfurous?) taste and I'm wondering why.
The dutch oven is a 6 Quart enameled model. I used about 3 pounds of Oso Sweet onions - generally a very sweet variety.
I followed what has been described as the Cook's Illustrated method: sliced onions placed in oiled DI with butter & salt, then put in 400 degree oven for an hour, stirred, put back in oven with lid ajar another hour, then finished stovetop with a browning deglazing iterations.
When the DI was removed from the 400 degree oven, the onions were greatly reduced in volume, and the top layer of onions were taking on a hint of gold color. But there was a lot of water in the bottom - most of the onions were simmering / steaming. After another hour in the 400 degree oven with the lid ajar there was still a large amount of water. Finishing on the stovetop, it took quite a while at medium heat to dry it out.
The onions had a somewhat acidic bitter taste. I am wondering what went wrong.
Is 400 degrees too high? It seems a bit much for what I think of as low and slow. Certainly this is a lot higher then the crock pots some people use to caramelize onions, and it seems higher then what I have used stovetop in my cast iron skillet for this purpose. I would have guessed a temperature in the range of 250 to 300 might have been better.
Might the onions have been too wet for too long?
Onions with too much acid for good Maillard reaction?
Would plain cast iron be much better for the Maillard chemistry?
Thanks for your thoughts!