Since you make a lot of this at one time, how long can they be stored in the refrigerator? Can they be frozen?

Caramelized onions keep for quite a few days in the refrigerator.

Though I have never frozen them before, I am sure they would freeze fine, as all of the liquid has been cooked out of them. I suggest freezing them in smaller batches so you can use as much or as little as you like.

I've been making caramelized onions for several years now and find they add a unique flavor to a modified Pasta Carbonara (caramelized onions, pancetta, 1 egg, fresh basil). They are also very nice in sandwiches and on grilled burgers.

I love using caramelized onions in meatballs and meatloaf. I often also add some roasted garlic at the same time. Nice round mellow but there flavours play in the background in a supporting roll to the "hero" ingredient.

Tip: For those watching their intake of fat cut back on the butter and add some hot water, cover and caramelize.

It seems like alot of onions to slice, any chance one could use a mandolin to make lighter work of this?

No worries. This is a great tool for cutting. I've done it before many times. For anyone that doesn't know what a mandoline is, cut and paste the link below into your browswer:

http://rouxbe.com/tips-techniques/151

Thanks Joe!

Using the mandoline, I sliced my onions this morning and that was fairly fast and painless. I've been cooking the carmalized onions up while I make my (whole wheat) pizza dough. It's amazing how much they cook down!

Next its pesto time, I'm planning on using walnuts as reccomended by a fellow comentator - can't wait to eat them end product of goats cheese, carmalized onion and pesto pizza!

Doesn't adding the salt this early in the cooking defer the caramelization process, ie. Caramelization aims to extract natural sugars and salt counteracts this process. Why not add the salt to taste once cooking is finished?

In this case you the salt is added to extract the moisture from the onions, which is necessary to caramelize them. Great point though.

I understand that because of all the moisture from the onion there isn't much time for the oil to burn/smoke, but the video instruct to get the pan over high heat and then use extra virgin olive oil which has a low smoking point, shouldn't grapeseed oild go better here?

You are correct it is better to use grapeseed oil. The recipe has been updated to reflect this...good catch, thanks!

I made these for the pork tapas (trying them out tomorrow). Wow they're good!! And so easy :D This is totally something I'll be incorporating into my everyday cooking

If I am making a smaller portion, should the onions be touching each other to keep the individual slices juicy?

Not sure how much you are making, but ultimately you do want to sort of keep the onions together; however this is mostly done so the pan does not burn in the bare spots.

It's important to use an appropriate sized pan for the amount you are doing, so you do not have too many onions in the pan as this would cause the onions to pile up and in this case they would steam rather than fry. Also, too little could cause the pan too burn in spots.

Hope this helps - cheers!

Thanks! My various foibles in the kitchen may end up helping others, so I'll risk bruising my pride here: 1/2 an onion in a large cast iron did cause "a few burn spots". One of these days I'll follow the recipe.

Just wondering can you caramelize onions in a pressure cooker? If so, what is the modified cooking time?

I have not done this myself but it is possible. Just keep in mind that you would really be using the pressure cooker more like a fry pan as you would not want to cover the pressure cooker with the lid otherwise the onions would steam rather than caramelize. Cheers!

can i make this with red onions??wil be the that the same result??/

You can caramelize red onions. The results will be similar but the color will of course be different due to the color of the onions. Cheers!

I used them in a potato tart which was awesome! I added a few cloves of minced garlic to the onions for added flavor. The potatos were excellent. Caramelize your onions. Slice some russets into rounds using a mandoline. Be carefull! I am missing a bit of my thumb this morning!! Ouch! Salt and pepper the potato rounds and then add your onions and mix throughly. Heat a cast iron or non stick pan on the stove and add about 2 tbls. of olive oil and a tbls. of butter. Put the potato and onions in the pan and pat them down flat.

Place about 2 or 3 tbls. of diced butter scattered over the top of the potatos. Cover with a piece of parchment paper and pop in the oven at 400 for about a hour. Remove the parchment paper for the last 15 minutes or so.
Remove from the oven. Place a plate over the pan and flip the pan over so the potatos are on the plate.
The bottom is crispy and golden brown. Cut into slices and serve. The caramelized onions really shine through in this dish.
Very rustic dish that goes well with steak or pork.

I did this recipe, but it took almost 3 hours to cook. I followed the recipe as accurately as I could. The only things I can think of that I did differently is I halved the recipe and used a non-stick pan. Any ideas what went wrong? It still turned out delicious though!

Yes a non stick pan won't do the job well, to caramelize the onions you actually need a regular pan that slowly "burns" the sugar released from the onions, a non stick pan does not allow for that. You also want to have a pan big enough so the onions have room to caramelized and not steam as they will if they are too crowded, hope it helps

Thanks. Is it ok to turn the heat up higher, or is it better to just invest in a new pan?
Thanks!

I gave up using non stick pans after working with a biologist who maintained an aviary indicated that seeds should never be toasted for his birds in a non stick pan. Doing so created toxic bird food. While I'm not a bird, I found it a bit scary. Before retiring I collected a dozen or more All Clad stainless pans, pots, and utensils. I have yet to manage to scorch my pans to a point where I can't get them clean. Making non stick pointless for me. But as always YMMV!

Stainless-steel pans have many advantages like Christophe mentioned above. Once you learn how to use them (there are many lessons in the school that teach about cooking in stainless-steel), your cooking changes. Both stainless-steel and non-stick have their purposes. Most manufacturers do not recommend heating non-stick over high heat. It is worth it to invest in a pan, but it's up to you. Cheers!