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Irresistible French Onion Beef Sloppy Joes

Irresistible French Onion Beef Sloppy Joes

A rich one-skillet sloppy joe made with caramelized yellow onions, savory ground beef, Worcestershire, beef broth, and thyme, finished under the broiler with melted Gruyère on toasted brioche buns. Ready in about 35 minutes.
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Prep Time 5 minutes
Cook Time 35 minutes
Total Time 40 minutes
Servings: 4 servings
Course: Dinner, Lunch
Cuisine: American
Calories: 615
Ingredients Equipment Method Notes

Ingredients
  

  • 1 lb ground beef, 80/20
  • 2 large yellow onions, halved and thinly sliced
  • 2 tbsp unsalted butter
  • 1 tbsp olive oil
  • 3 cloves garlic, finely minced
  • 1 tbsp tomato paste
  • 1 tbsp Worcestershire sauce
  • 1/2 cup low-sodium beef broth
  • 1 tsp fresh thyme leaves or 1/2 tsp dried
  • 1/2 tsp onion powder
  • 1/2 tsp black pepper, freshly ground
  • 1 to taste salt
  • 1 tsp balsamic vinegar optional
  • 4 oz Gruyère cheese, freshly grated approx. 1 cup loosely packed
  • 4 whole brioche or potato buns, split and toasted

Equipment

  • Large Heavy Skillet (cast iron preferred)
  • Wooden spoon
  • Baking Sheet
  • Broiler
  • Box Grater

Method
 

  1. Caramelize onions: heat butter and oil in a large skillet over medium-low. Add onions with a pinch of salt and cook 20 to 25 minutes, stirring every 4 to 5 minutes, until deeply golden and jammy.
  2. Brown the beef: push onions aside, raise heat to medium-high, add ground beef and cook undisturbed 2 minutes, then break apart and cook until fully browned, about 4 to 5 more minutes. Drain excess fat if needed. Stir beef and onions together.
  3. Add aromatics: stir in garlic and tomato paste. Cook 1 to 2 minutes until paste darkens slightly and garlic is fragrant.
  4. Build the sauce: add beef broth, Worcestershire, thyme, onion powder, and pepper. Simmer uncovered 5 to 7 minutes until glossy and thick. Stir in balsamic vinegar if using. Taste and season with salt.
  5. Broil with cheese: preheat broiler. Place toasted bun bottoms on a baking sheet, spoon filling over each, top with grated Gruyère. Broil 2 to 3 minutes until melted and lightly golden. Watch closely.
  6. Serve immediately with bun tops placed on. Best eaten hot while cheese is still stretchy.

Notes

  • Never rush the onion caramelization - low heat and 20 to 25 minutes is what creates the French onion flavor.
  • Always toast buns before filling to prevent sogginess.
  • Grate Gruyère fresh from a block for the best melt.
  • Filling keeps refrigerated for up to 4 days and frozen for up to 2 months.
  • Reheat filling on the stovetop with a splash of broth - toast a fresh bun and broil cheese again rather than reheating the assembled sandwich.