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World's Easiest French Onion Soup

World's Easiest French Onion Soup

I've made this soup with two different slow-cooking methods, which really just vary depending on how much time you have and what you're in the mood for; you'll also see notes for ingredient options as I've made it both 'regular' and vegetarian. I said it was easy and flexible!

Course Soup
Keyword vegan, vegetarian
Prep Time 10 minutes
Servings 6
Author Annie

Ingredients

  • 3.5 lbs onions, sliced, with those slices halved this equates to 4 large onions; can use yellow, sweet, red or a mix of all (don't recommend using only red)
  • 3 Tbsp unsalted butter use oil to make vegan
  • 1 Tbsp brown sugar
  • 6 c beef broth or vegetable
  • 3 Tbsp balsamic vinegar, red wine or Worcestershire sauce use whatever you have in whatever combination you fancy - I recommend 1 tsp of Worcestershire sauce and the remainder either vinegar or red wine if you have some open; this helps give an umami boost to the soup
  • 1 Tbsp sherry, brandy or cognac optional, but adds a classic yet subtle taste
  • black pepper
  • salt to taste

Instructions

Overnight Method

  1. The night before you want to eat, slice the onions (see blog post above for guidance on which way to slice), and then cut those slices in half so that they'll easily fit on a spoon when you're eating.

  2. Add onions and butter or oil to a large slow cooker, and set on low heat for 8-10 hours (depending on how long you'll be asleep - I like to start it before bed, and let it go until right before I wake up - my model shifts to 'keep warm' when the time is up). I don't set it to beyond 10 hours because I want to make sure I can check on things when I wake up.

  3. Wake up to the smell of delicious caramelizing onions! They should be golden brown and have released a lot of liquid at this point. Stir the onions around, scraping down the sides if necessary. It's possible some onions around the edges may have gotten very brown but that just means more flavor :) At this point, if you have any interest in saving some caramelized onions for future recipes, remove some now - I removed about a cup and a half, so I still had plenty left for the soup.

  4. Since I was 1) working from home, 2) loved the smell and 3) didn't need to eat it until dinner, I let the onions continue to cook on low all day. Their color and flavor deepened even more over the next six hours.

  5. Around 2pm, I added the broth and the 3 Tbsp of additional flavor (this time, balsamic vinegar and Worcestershire sauce) - don't add the brandy/cognac/sherry yet, if using, or the salt/pepper - and set back on low for 4 hours.

  6. Right before serving, I stirred in the cognac and some freshly ground black pepper. After tasting, I decided it didn't need additional salt as the vegetable broth I used was fairly salty.

  7. It's traditional to spoon the soup into ovenproof bowls, top with crusty bread covered in gruyere or swiss cheese and then melt it under a broiler - and I mean, that's delicious and you should definitely do that. However, the soup also tastes amazing without that, or with just some leftover pizza crust and parmesan cheese, if that's all you happen to have on hand at the moment...just saying ;)

One-Day Method

  1. Place the sliced onions and butter or oil in the slow cooker in the morning, and set on low for as long as you'll be gone - 6-8 hours.

  2. Return home, welcomed by the smell of delicious caramelizing onions. Crank up the heat to high, add your broth, 3 Tbsp flavorings and 1 Tbsp alcohol (if using), and let it cook for at least 1 more hour, ideally 2, so the flavors can meld together.

  3. Season with black pepper and salt, if needed. Serving suggestions are the same as above.