Onion Tart – Perfect for your holiday party or New Year’s brunch

Onion Tart

This onion tart is the perfect complement to just about any sparkling wine. Take it to an office holiday potluck, serve it at your Christmas or New Year’s Eve party, or best of all for a holiday brunch. Then make it all year long if you want, and I believe you will want.

If you’ve never had one, or only had them improperly prepared, an onion tart may not sound like the most appetizing dish. It probably doesn’t sound like something that would be great with wine either. Anyone who has ever had a delicious wine rendered undrinkable by the sulfuric compounds in raw onions is probably running in horror at the mere suggestion of it. They really should grow a pair and quit running from any sort of food, unless of course it was “cooked” by Sandra Lee.

A raw onion has sulfuric compounds in its cells that combine with an enzyme when the cell walls are broken. This chemical reaction is a defense mechanism that is often quite effective, especially against  wine. But when we cook onions these compounds change. Sauteing or cooking quickly in fat produce the flavors we expect in cooked onions, but when cooked painfully slow and low magic occurs and there are few things that combine sweet and savory together quite so perfectly. An onion tart is a nearly perfect expression of this culinary marvel.

Before we get to the recipe, let’s look at caramelizing onions. At its core, this means that heat will be applied to sugar which will then coat the onions. But how do we accomplish this? I have seen so many variations on the original process that claim to improve upon it, but some classics are classics because they don’t need to be improved. The Ramones didn’t need a keyboard player or a better wardrobe and your onions don’t need added sugar or anything else added to them. Fat, a sprinkle of salt, low heat and a bunch of onions in a heavy pan are all that is required to achieve perfection. Keeping it simple and doing it right is good advice whether you are starting the world’s greatest punk band or caramelizing onions. Seriously, both Blink 182 and burnt onions suck. A lot.

The recipe for this tart calls for bacon, so I use the rendered bacon fat to caramelize onions, but butter works great and is what I typically use for non-bacon dishes. A lot of recipes call for very thinly sliced onions, but I prefer thick slices. The thin slices cook quicker, and many would argue that they provide a more delicate taste and texture, all of which are true, but the thick slices have their charms as well. Since I’m not in a hurry when I make this dish, the thicker slices retain more onion flavor while providing more texture, sort of like al dente pasta does. While trying very hard to resist making an awful pun, I have to say it makes little difference to the success of this recipe how thin or thick you slice the onion, provided you do the rest of the processes correctly. Trust me, no one will complain either way.

When making this I cook the bacon first, which is also best done in a heavy pan at lower temperatures, and when the strips are nearly done I turn the burner down even more. Once I remove the bacon I start slicing onions. This gives the pan and the fat a chance to cool down even more. If there is too much fat in the pan, pour it off and use it in something else later. When the onions are all sliced add them to the pan all at once and sprinkle them with a pinch or two of salt.

The reason for the low heat and the salt is that we want to pull out much of the water inside the onion slices. The low heat also keeps the onions from burning and turning into culinary Blink 182. Make sure and move the onions around every few minutes at first so that they all get a little heat, but as they start to give up the water they won’t need to be stirred or flipped as often. Just don’t forget about them. I have come back after 20 minutes and been surprised that they haven’t burned, but that’s pushing it.

Once the onions are all wilted and translucent it is alright to turn the heat up just a touch, but it isn’t necessary and that will require a lot more diligence to keep them from burning. But if you like living dangerously after taking all of that time to get to this stage you might be rewarded with a little more flavor. The reason for that is that in addition to the natural sugars caramelizing, the Maillard reaction is also contributing to the party and the additional heat may help it along, as long as care is taken to not burn the other sugars. If you’re not a foodie, the Maillard reaction might be geekier than you care to know about. Suffice it to say that it is the results of sugars reducing and doing the Lambada with some bad boy amino acids. In even simpler terms, while it produces entirely different flavors in each, it is why both your steak and your toast are brown and tasty. As you can see, even if you had never heard of the Maillard reaction, you are probably a fan.

As our beautiful translucent onions begin to brown and take on color it becomes decision time, a decision that gets easier with experience, but one you’ll have to make on your own. The longer they cook, the darker our onions get. The darker the color on the onions, the sweeter and more flavorful they will be. Then in an instant we have Blink 182, and we’re back to square one and dinner will be served around midnight. I suggest going for a good amount of pretty brown on about half of the onions, tasting one of the darker ones and judging from there whether to push your luck or not. As long as they are sweet and not sulfurous they will be tasty.

One last thing before we get to the recipe is to decide what kind of onions will work best. It would seem like using sweeter onions would be best, and if time is short actually might be, but if there is time to do it up right then the plain old yellow onion is usually best. Some people prefer red onions, but I don’t think they add anything to the end result. The humble yellow onion, and its white counterpart work best for a lot of reasons. First of all, you probably have them on hand at all times. Secondly, they are cheaper. And perhaps most importantly, they tend to taste sweeter than “sweet” onions when caramelized. The reason that sweeter varieties of onions taste sweeter isn’t necessarily due to having more sugars. Remember that protective chemical reaction we discussed earlier? That masks the sweetness that the raw onion contains, and in sweet varieties there are fewer of the compounds that cause the reaction, hence we taste the sugars. Caramelization levels the playing field on the palate, but not the wallet. I’m all for paying extra for better ingredients when they produce better results, but in this case there is no reason to spend more money to end up in the same place. Use yellow onions. Also, about halfway through the process, for this recipe add the apple listed below.

Enough food geekery? Hungry? Ready to cook? Without further ado…

A delicious, stupendous, and frankly amazing Onion Tart Recipe


1 cup caramelized onions (about 4 medium onions)
4 eggs
1 diced apple (use a baking variety that won’t turn to complete mush)
8 oz creme fraiche
4 strips of bacon
10 ounces Cambozola cheese
1 deep pie crust, or 2 flatter ones.
Pinch of dried thyme
Salt and pepper

Preheat oven to 400°F

Since we’ve already dealt with the serious cooking part of this recipe, the rest is mainly assembly. Whisk the eggs and creme fraiche together along with the herbs and seasonings until combined. Creme fraiche is readily available in most supermarkets these days, try looking for it near the fancy cheese. If you don’t have any creme fraiche substitute heavy cream, but do not use sour creme as some recipes suggest. Spread the onion and apple mixture evenly in the bottom of the pie crust(s), crumble the bacon over the top, then add little blobs of the soft cheese all around. Pour the egg mixture over the top. Back for about 30-40 minutes until the top is nicely browned. If your oven is as crappy as mine, make sure and turn the pan after about 20 minutes to ensure semi-even cooking. That’s all there is to it. Let it cool until about room temperature and serve.

Note that I did not say anything about the crust, other than that it is required. Obviously the better the crust is, the better the dish will be. There are a million pie crust recipes available on the Web, just have Senor Google fetch you one. I prefer Alton Brown’s personally, but I have to confess that I have no problem with using a store bought crust for this dish. In fact, I made two of these with store brand frozen crusts the other night for a sparkling wine tasting, and Amy took the extra one into work. After tasting it one of her co-workers told her, “Dude, I want your husband in the worst way!” (Imagine what serving this at a New Year’s Party might get you?) Apparently Amy was too much of a lady to reply, “Dude, at his age that’s the only way!” Well, if she did reply that way, she was at least enough of a lady not to to tell me she said it.

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