Onion soup, with croutons and melted cheese/Photos by Donna Turner Ruhlman

Onion soup, with croutons and melted cheese/Photos by Donna Turner Ruhlman

Donna wanted to change the banner photo on my Facebook page and it got so many likes and comments that I knew it clearly struck a wintery warmth chord in dreary March. I’ve posted this before and here it is again from, Ruhlman’s Twenty, which looks at 20 key concepts that underlie all of cooking. This key concept is water. This onion soup requires nothing but onions and water for the soup part.

Plan ahead when making the soup because the onions take a long time to cook down, from a few hours to as many as five if you keep the heat very low, though you need to pay attention only at the beginning and the end. Before the onions caramelize, they’ll release copious amounts of water (be sure to taste this liquid!), which must cook off first. You can simmer the onions hard if you want to reduce the cooking time; be sure to tend the pot and stir often, or the onions can stick and burn. You can also caramelize the onions a day or two in advance, and refrigerate them for a quick delicious soup during the week, or even freeze the onions for up to a month. If you do this, the soup can be finished in the time it takes to heat the water and melt the cheese on top.

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Traditional French Onion Soup

  • 1 tablespoon butter
  • 7 or 8 Spanish onions (7 to 8 pounds/3.2 to 3.6 kilograms), thinly sliced
  • Kosher salt
  • Freshly ground black pepper
  • 6 to 12 slices of baguette or any country-style bread (it’s best if they cover the width of your serving bowls)
  • 1/3 cup/75 milliliters sherry
  • Red or white wine vinegar (optional)
  • Red wine (optional)
  • 1/2 to 3/4 pound/225 to 340 grams Gruyère or Emmanthaler cheese, grated
  1. Use a large pot, with a capacity of about 7 1/2 quarts/7.1 liters, that will hold all the onions. An enameled cast-iron pot will provide the best surface. Place the pot over medium and melt the butter. Add the onions, sprinkle with 2 teaspoons salt, cover, and cook until the onions have heated through and started to steam. Uncover, reduce the heat to low, and cook, stirring occasionally (you should be able to leave the onions alone for an hour at a stretch once they’ve released their water). Season with several grinds of pepper.
  2. Preheat the oven to 200°F/95°C. Place the bread slices in the oven and let them dry completely (you can leave the slices in the oven indefinitely, as the heat is not high enough to burn them).
  3. When the onions have completely cooked down, the water has cooked off, and the onions have turned amber—this will take several hours—add 6 cups/1.4 liters of water. Raise the heat to high and bring the soup to a simmer, then reduce the heat to low. Add the sherry. Taste and season with salt and pepper as needed. If the soup is too sweet, add some vinegar. If you would like a little more depth, add a splash of red wine. I like the onion-to-liquid ratio with 6 cups of water. But if you’d prefer a slightly more delicate soup, add 1 cup/240 milliliters water.
  4. Preheat the broiler/grill. Portion the soup into bowls, float the bread on top, cover with the cheese, and broil/grill until the cheese is melted and nicely browned. Serve immediately.

Serves 4 to 6

 

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© 2013 Michael Ruhlman. Photo © 2013 Donna Turner Ruhlman. All rights reserved.