I am looking to make a large amount of French Onion soup (for ~16 servings), and rather than spend hours in front of a skillet (as I would have to do several batches), I am looking for an easier way:

  • could I bake a large amount (~20 onions) in an oven to achieve a similar effect?

  • should I put them in a pressure cooker?

  • are there even better alternatives?

In particular if anyone has advice as far as what else or details as to how to make it work (temperatures for ovens, convection/broil, pressure to cook at, etc. (I already read this, which while it would help, aims mostly at speeding it up & not doing a large amount which is more along the lines of what I am thinking) I would be interested, as I don't want to experiment with a large quantity of onions several times in order to get it right

P.S. - I am using yellow onions, although I'd imagine this would apply to all onions

P.S. #2 - what do restaurants do?


3 Answers 3


You can caramelize onions in the oven to do large quantities. This isn't less effort, and it actually takes longer, but it does allow you to do really large quantities; I did 20lbs of caramelized onions for one Polish dinner I was serving this way. Since I haven't been able to find a website with this method, here it is:

  • heat oven to 325F/160C
  • fill a hotel pan or baking pan with sliced onions to a depth of about 3/4"/2cm
  • toss the sliced onions with vegetable oil or melted butter and a little salt (and optionally a little sugar)
  • cook, uncovered, in oven for 1 hour to 90 minutes, stirring every 10 minutes.

The reason for the 2cm depth of onions is to keep them from burning in the oven, which they tend to do if spread thinner. Also, if you have a gas rather than electric oven, you may need to add a little water occasionally to prevent burning.

Althernately, Kenji of Serious Eats has a formula for cooking caramelized onions over high heat, and thus cooking each batch faster, without losing flavor. This would allow you to jump through several batches.

  • The oven method was given to me by a professional caterer, so I suspect that at least some restaurants use it.
    – FuzzyChef
    Commented Jan 11, 2019 at 17:50

Use a pressure cooker if you have one. I saw this in modernist cuisine but the above mentioned kenji (legend) has a discussion. The total cooking time is under 30 minutes.

  • Can you incorporate the minimum necessary information into the answer such that it's not dependant on the link? Commented Jan 12, 2019 at 16:53
  • Quick note that Kenji's pressure cooker method results in a lot of liquid, which is great for soup. The big advantage is time and not having to watch over the cooking.
    – mike
    Commented Jan 17, 2019 at 18:43

Caramelizing onions works great in a slow cooker. Slice 5 extra large sweet onions in half, then in fairly thin half moon slices. Place them in a 6 qt (5.7 liters) slow cooker with a splash of water for 12 to 15 hours. Like magic they turn brown. Stir regularly after they have cooked several hours to even out the browning process. This also produces a small amount of onion stock which will go well in your soup.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.