Categories: Eats, Life Style

Slow Cooker French Onion Soup

Hey, What’s Cookin’?

Today we are going to indulge ourselves in a restaurant classic. It’s a delicious soup that you probably haven’t made at home because it’s very time-consuming and somewhat tricky, and the traditional topping for the soup is not m.e.l.t.-compliant. But there’s no need to deny yourself the soup itself, which consists of a gloriously deep-flavored beef broth with caramelized onions. Yes, I’m talking about French Onion Soup.

Onions are not only one of the most flavorful vegetables around, they also provide important nutrients and health-promoting phytochemicals. High in vitamin C, onions are a good source of dietary fiber, and folic acid. They also contain calcium, iron, and have a high protein quality (ratio of mg amino acid/gram protein). Onions are low in sodium and contain no fat.

Most importantly, onions contain quercetin, a flavonoid (one category of antioxidant compounds). Antioxidants are compounds that help delay or slow the oxidative damage to cells and tissue of the body. Studies have indicated that quercetin helps to eliminate free radicals in the body, to inhibit low-density lipoprotein oxidation (an important reaction in the atherosclerosis and coronary heart disease), and protect and regenerate vitamin E (a powerful antioxidant). Quercetins are not lost through baking or frying, but they can be lost in cooking water if boiled. That’s one reason for using a slow cooker; as long as you keep the setting on Low during the entire caramelization/soup making process, you should be able to retain the full amount of antioxidents. Besides, any quercetin lost from the onions will end up in the broth!

You owe it to yourself to see just how delicious this French onion soup is–without the toppings. The slow cooker does all the long, fussy work of caramelizing the onions and then simmers the soup besides. Any leftovers will freeze well and be convenient for another great meal on a chilly day.

Slow Cooker French Onion Soup

Serves: 4-6

Ingredients to caramelize the onions:

  • 3 lbs yellow + 1 large red onion; thinly sliced into quarter moons (do not use Vidalias-they are too sweet)
  • 3 tbs unsalted butter, melted
  • 1 tbs olive oil
  • 2 tsp kosher salt
  • 1/2 tsp freshly ground black pepper

Ingredients to make the soup:

  • 1/2 cup red wine (use 2 tbs. red wine vinegar if you need a substitute)
  • 6 – 8 cups good quality, low-sodium beef broth
  • 2 tbs balsamic vinegar
  • 10 sprigs fresh thyme
  • 2 bay leaves
  • 1 large clove garlic, whole
  • 2 teaspoons dry sherry (“cooking sherry” is not acceptable)


  1. Prepare the onions. Place the sliced onions in a 5-quart or larger slow cooker. Stir in the butter, oil, salt, and pepper.
  2. Cook on LOW for 12 hours. Cover and cook on the LOW setting. Stir every 2 hours or so if possible. The onions should become dark golden-brown and soft.
  3. Make the soup. Stir in the wine, 6 cups of broth, vinegar, thyme, bay leaves, and the garlic clove.
  4. Cook on LOW another 6 to 8 hours. Cover and continue cooking on the LOW setting for 6 to 8 hours. This is flexible; as long as your slow cooker holds moisture well (wrap a towel over the lid if quite a lot of steam escapes), you can cook the soup for hours. Longer cooking will only intensify the flavors. Taste and season with more salt and pepper if needed. You can add more beef broth if you feel the soup needs it.
  5. Serve the soup. Add the sherry to the cooker and stir. Ladle the French onion soup into traditional soup crocks or bowls.

Notes: If you are having this soup as a cheat meal, you can cover the soup with the traditional toasted bread and cheese. Use French bread or ciabatta sliced 1/2″ thick and cover it with grated Gruyére or smoked Gruyére cheese. Traditionally, one broils the bowl of soup with the bread/cheese on top. But you can just as easily broil the bread/cheese separately on a foil-lined baking sheet, and then place the toasts in the bowl of soup.



Photograph via butchersniche

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