Caramelized Onion Tart using White Onions

My Finished Tart...Delicious!

As I've mentioned before, I think we're pretty spoiled here in Mexico in terms of how many ingredients are available to us that we're used to from the States, at least when compared to other places around the world!  But I have still been sad to find the lack of different types of onions!  City Market has a decent selection given that they have cippolini and other small varieties, but it's very difficult to find common yellow onions.  When I see them at Chedraui and Superama, I snatch up as much as I think I could possibly use before they go bad...but I always run out and want more.  And forget about finding really sweet onions, like Vidalias!

Regardless of not having "exactly" the right type of onion, we're fortunate that white and red onions are still pretty versatile.  And I even discovered recently that you CAN get wonderfully delicious, caramelized onions using white onions, so I thought I'd share that process with you.

I found this recipe on FineCooking.com for a Rustic Onion Tart with Olives, Capers and Anchovies that sounded amazing, so I decided to make it for a dinner party we were headed to.  I figured I was going to have to wrestle with the onions since I was using white onions instead of yellow onions and I did, but it wasn't as difficult as I thought it would be and the tart turned out quite tasty.


My Kitchen all prepped to caramelize my onions...
I was using the bread maker to make the pizza dough. 
Can you tell I was having fun?

Here's the thing about white onions vs. yellow onions...they have less natural sugars in them, so that makes caramelizing much harder.  (The definition of "caramelization" is the breaking down of sugar molecules at around 300°F/150°C into many different chemical compounds.  As Harold McGee writes in the bible of food science, On Food and Cooking, "Heat transforms table sugar, a sweet, odorless, single kind of molecule, into hundreds of different molecules that generate a complex flavor and rich brown color."  Caramelization is, in short, absolutely amazing.  We all know how delicious caramel is, and you can make that at home using only sugar and water!  The magic is in those special chemical reactions.)

In the middle of the caramelization process...almost there...

Back to the onion tart recipe...I had to tweak it a little bit.  It calls for heating 1 Tbsp of olive oil in a 12-inch skillet over medium high heat until shimmering hot.  At that point you add the onions (the recipe of course calls for yellow but I substituted white) and a generous pinch of salt.  You then cook them, stirring constantly, until the onions are golden and softened.  With sweeter yellow onions, this only takes about ten minutes.  I knew it would require a lot more effort with the white onions (and a little bit of cheating), so at the same time I added the onions and the salt I added about 1/2 Tbsp of sugar into the skillet as well. I reduced the temperature slightly (just above medium) and while the onions cooked, I stirred them almost constantly with a wooden spoon.  (If you don't stir, they'll burn.)  As the onions caramelized, much of that flavor was stuck to the bottom of the pan.  I used my wooden spoon to continually scrape up those yummy brown bits, incorporating them back into the onion mixture which helped to evenly caramelize the onions.  (If you have a spot in your pan that is difficult to scrape up, it helps if you gather some onions on top of it, use your wooden spoon to squeeze out some of their juices, and then scrape up the caramelized spot.)  I have to admit, the whole process ended up taking about 35 minutes until I felt my onions were caramelized enough, but when I was finished the onions were incredibly sweet and caramel-ly delicious!  They blended perfectly into this tart recipe, and it was a big hit.  

Assembling my tart before baking. 
Notice the final dark color of the caramelized onions,
located on the blue plate in the middle top.

You can use this method for cooking caramelized onions for any application, whether it be for classic French onion soup, inside a quiche, to serve on top of a sandwich or burger, or even to simply pair with some pan-fried potatoes for breakfast.  Let me know how your caramelized onions turn out, and what you used them in!