sweet
tart
spicy
savory
salty
oniony
you know you want some
onion syrup
300g sugar
100g Vidalia onion juice (about 1 large onion, put through a juicer)
200g dry red wine
150g red wine vinegar
50g balsamic vinegar
50g extra-virgin olive oil
5g fleur de sel
1.5g sichuan pepper, coarsely ground
1 medium Vidalia onion, cut lengthwise into 8 wedges and separated into petals.
Place sugar and onion juice in a large saucepan. Stir until sugar is evenly wet. Cover pan and set over medium heat. Cook for 3 minutes, then remove cover and turn heat up to medium high. Cook syrup to 360F/182C, or until medium golden and smells like toasted onions.
Immediately remove pan from heat and carefully add the wine to the pan. The hot syrup will sputter and boil, add the wine slowly until it calms down. Return pan to stove and continue cooking on medium high heat. When the syrup has dissolved in the wine, add all of the remaining ingredients. Adjust the heat to maintain a full rolling boil and cook the syrup until it reduces and thickens to the consistency of maple syrup. This can take up to 10 minutes.
Allow syrup to cool slightly and strain out the onion pieces. Store syrup in refrigerator for up to one month.
Playing with Fire and Water 
Well, this is interesting: I would never have thought about putting an onion into a juicer (Jack Lalane, where are you?).
I’m thinking about how to make this into a savory dessert, though the immediate thought of a “liver and onions” variant as an ice cream with syrup doesn’t sound quite palatable. Foie gras mousse perhaps, but then again, you’re just going to quietly pull out something wild and spectacular in the next couple of days, aren’t you? Can’t wait.
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First you write “…add the wine to the pan,” and then “add the syrup slowly.” Should the “syrup” be “wine”?
Have you calculated the Brix value for the final syrup? It looks like it would be high enough for this to last years rather than a month.
How do you plan to use the syrup? Does the acid pull through in the final flavors or is it mostly sweet. Seems like this would make a great granité.
Why a sweet onion for the juice rather than an onion with a higher sugar level? Cooking an onion drives off the pyruvic acid that makes it sharp, and Vidalia onions are called “sweet” because of a low acid content, not a high sugar content.
All of the above aside, I’m always happy when “playing with fire and water” pops up in my RSS reader. Your posts are the most creative and inspirational—for a foodie like me—on the Internet.
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You’re right… I do want some. So I’m going to make some.
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I do! I do want some!That sounds wonderful. It reminds me a bit of cipollini onions in balsamico.
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Onion milkshake, definitely.
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Foie gras mousse? that would be pretty wild and spectacular! so would chicken liver pate.
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oops. thanks for catching the error. all fixed now.
I can’t measure the Brix as I don’t have a refractometer, but you’re probably right in assuming that it would keep for longer than a month.
The acid is definitely present and balances the sweetness, but I’m guessing that the sugar levels are too high for it to freeze properly.
Good question about the choice of onion— it’s simply what I had on hand.
Thanks for subscribing Peter, and for the huge compliment.
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Larry, if you do, I’d be interested to know how you end up using it.
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Thanks John, you’re right… it is a variation of agrodolce.
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Definitely indeed!
I was originally going to flavor the syrup with vanilla, but went with the spicy/floral sichuan pepper to swing it further to the savory side, but it would be fantastic with vanilla ice cream in a milkshake (or a foie sundae via Ivan’s suggestion).
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Here’s a possible use: choux à la mousse de foie gras (http://xrl.us/bho9ef) topped with the onion syrup.
Or maybe a parfait fois gras mousse and onion syrup?
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Haven’t put together the entire idea yet but I’m leaning towards something that involves your vidalia syrup and a pickled peach sorbet I’ve been working on. It’s been really busy at work, tourist season, so I haven’t had as much play time lately. The two are working nicely together in my head… I just need to get them together so I can figure out who else to invite to the party.
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I tried making an onion granité today starting with 270 grams of juice extracted from a couple uncured yellow onions and 102 grams of sugar. I only cooked it to about 102°C so the color is still light green. It froze OK even though the Brix is at about 32. The flavor is a little sharp so tomorrow I’m going to cook it some more to try to drive off a bit more of the pyruvic acid.
Also today, I coded a new tool to approximate the Brix value of a syrup or to tell how much sugar to add to obtain a certain Brix value. It’s at http://xrl.us/betd26
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very nice… I’d invite pork, but it’s your party.
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Great resource— not only for calculating Brix, but for brine, nitrate, and low temp cooking. Thanks for doing the work!
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Every time I run into some pencil and paper calculation I have to do that requires more thinking than basic arithmetic, I add it to the tool set. If you can think of any others, please let me know.
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Ok, Wow, Peter’s calculators are going to change my life. Love the passive sous vide calc. The onion syrup sounds appealing. Stonewall Kitchens sells a commercial garlic and onion jam that is approximately in this flavor range, minus the Szechwan peppercorn. I sometimes use it as the base for a sauce when I don’t have time to develop deep flavors.
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Oh yeah!!! The possibilities are playing through my mind right this minute. Yum!
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mmm I think this is going to be great and find its way into a lot of my cooking, Chinese in particular.
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