The other day, Jackie and our dinner guest had a yen for calf’s liver, something I love to cook but hate to eat: Liver is one of only two foods to which I have a profound aversion. When I went to the butcher to buy them some, I got myself a nice pork chop, then got to thinking about an accompaniment that would do the job for both – beyond the inescapable mashed potatoes.
Caramelized onions spiked with vinegar was the answer, as it often is. When I’ve made these in the past, I’ve always done it by fussing over a skilletful of onions and butter (and sometimes sage leaves), getting them brown and soft, then deglazing the pan with vinegar and simmering for a bit. And it does take some fussing, which I can live without when I have other things to do, such as looking at videos on YouTube.
That is not (always) a waste of time, for it was on YouTube that, in a TV segment from 15 or 20 years ago, I saw the late chef-restaurateur Joël Robuchon and the chef of the marvelous Epicure restaurant in the Paris hotel Le Bristol, Eric Frechon, employing a clever, simple technique to make the perfect vinegared caramelized onions (for a dish of calf’s liver, as it happens). How simple is it? Well, once you’ve shoved the pan of onions into the oven, it requires no intervention apart from an inspection part way through the cooking.
Though I’ve retained the technique, I’ve adapted the recipe, adjusting timing, oven temperature and proportions to yield a chestnut brown, sweet-tart, versatile onion “jam” that would be as good on a hamburger as by the side of a slice of liver (or a pork chop). If you’d like to add a few whole fresh sage leaves to the pan, feel free.
- 1-1/2 pounds onions, red or yellow (about 4 medium onions), peeled, halved and cut into 1/8-inch slices
- 1 Tablespoon butter
- 1/3 Cup sherry vinegar
- 1/4 Cup wine vinegar (red or white)
- 1/2 Cup water
- 1/2 Teaspoon sugar
Heat the oven to 360º F. Cut a circle of parchment paper to fit a small casserole or deep oven-proof skillet (say, 8 inches in diameter) and pierce it in several places to create vent holes. If you have no parchment paper, use a double layer of waxed paper; do not use aluminum foil.
In the casserole or skillet, melt the butter over medium heat. Add the sliced onions along with a generous sprinkling of salt and stir to coat with butter (I use tongs). Continue to cook, stirring regularly, until the onions have grown slightly limp, about 5 or 6 minutes.
Add the vinegars, the water and the sugar, and bring up to the simmer. Lay the circle of parchment paper on top of the onions. Do not cover the pan.
Place into the oven and go about your business.
After an hour, take a look at the onions and give them a stir; if they seem dry, add 2 Tablespoons of water. And if they show signs of over-browning or sticking, lower the oven temperature to around 350º F.
Check again after another 30 minutes (i.e. after an hour and a half in the oven). When done, the onions will be a beautiful brown, glossy and very tender, so continue checking every 10 or 15 minutes (adding a spoonful of water as needed) until that’s how they are. The total time in the oven should be 90 minutes to two hours.
When they have cooled enough to taste without burning your tongue, add salt as needed to balance the tartness of the vinegar, remembering that this will be served not as a vegetable but as a relish alongside a principal ingredient such as liver, pork chops or Italian-style sausages – or on a hamburg