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French Onion Dip Sandwiches (Slow Cooker)

Rated as 4.73 out of 5 Stars

"This combines the greatness that is French onion soup with French dips. It is not supposed to be an 'authentic' French dip recipe, because authentic is often boring. These are yummy sandwiches for those that like roast beef and French onion soup. It is mainly on the slow cooker, but it requires a bit of prep on the stove, too."
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7 h 51 m servings 615
Original recipe yields 8 servings (8 sandwiches)


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  1. Heat 3 tablespoons olive oil over medium heat in a large, deep pot. Add onions and toss to coat with oil. Cook, stirring often, until softened, about 15 minutes. Add 1 tablespoon butter. Cook and stir until onions start to brown, about 15 minutes more.
  2. Stir sugar and 1/2 teaspoon salt into the onions in the pot. Continue to cook, stirring once halfway through, until onions are well-browned, 10 to 15 minutes more. Mix in garlic and cook for 1 minute more.
  3. Stir 3 tablespoons of water into the pot, scraping bits from the bottom. Let simmer for 3 minutes; repeat with an additional 3 tablespoons water. Simmer for 3 minutes more and repeat. Add vermouth; scrape bits from the bottom and sides of the pot. Cook for 4 minutes more. Add stock, Worcestershire sauce, soy sauce, thyme, and bay leaf. Simmer for 10 minutes; do not boil. Add black pepper. Discard bay leaf. Remove pot from heat and allow soup to cool. Pour into the slow cooker, but don't turn it on.
  4. Trim any excess fat from the rump roast. Sprinkle all sides with salt and pepper. Heat remaining 2 tablespoons olive oil in the pot over high heat. Cook the meat, holding it down with tongs, until browned on all sides, about 10 minutes. Transfer meat carefully to the slow cooker. Spoon the soup over the meat so that it is topped with a few onions. Cover and cook on Low for 4 hours.
  5. Remove meat from the slow cooker. Slice it diagonally and return slices to the slow cooker. Continue to cook on Low for 2 hours more.
  6. Preheat the oven to 350 degrees F (175 degrees C). Spread rolls with remaining 2 tablespoons butter; place face-down on a baking sheet.
  7. Bake rolls in the preheated oven until beginning to brown, 8 to 10 minutes. Remove from the oven, flip, and sprinkle with Gruyere cheese. Set oven rack about 6 inches from the heat source and turn on the oven's broiler. Broil rolls until cheese is slightly bubbly and lightly browned, 2 to 4 minutes.
  8. Remove meat from the slow cooker using a slotted spoon. Place on the rolls. Serve soup on the side for dipping.


  • Cook's Notes:
  • Trip-tip roast also works in this recipe.
  • I used a mix of white and yellow onions.
  • White wine or sherry can be substituted for the vermouth if desired.

Nutrition Facts

Per Serving: 615 calories; 33.5 34.1 42.2 110 785 Full nutrition

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Read all reviews 23
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I didn't bother with the fry pan. I just put the butter and sliced onions in crock pot and let them cook until they were soft just like I would do for onion soup. Saves time and extra pans

This recipe turned out great! I admit I was worried at the 4 hour mark by how tough the rump roast was when I took it out to slice it diagonally , but it was falling apart at 6 hours. Plus, I ...

Excellent recipe! Recommend making it when you have about an hour in the morning for prep, but it is so worth it!

Great recipe! Delicious! I browned the meat in a frying pan first and then cooked the onions in the same pan. It seems to be a more natural order of events.

This was great for my family with simple prep on a busy Sunday afternoon. Absolutely delicious! I threw in a few extra onions, mushrooms and carrots just b/c the beef seasoning stews them up s...

These were mouthwatering good. Try it. They are delicious. A little time consuming in preparation, but worth it.

My entire family LOVED this sandwich! Making it again today.

Excellent. Used a top sirloin from Costco and actually cooked it longer than suggested but didn’t matter. Used the beef broth gel packs dissolved in water. Maybe try the beef broth in tetrapa...

The first day it was the best and all my friends loved it. Day 2 not so good. alittle dry and no broth left. Had to make my own. But use cold and hot dip I give 5 stars.