Ingredients
Scale
- 2 large yellow onions thinly sliced
- 2 tablespoons unsalted butter
- 1 teaspoon kosher salt
- ½ teaspoon sugar optional
- 1 teaspoon Worcestershire sauce
- ¼ cup beef broth or beef stock
- Freshly cracked black pepper
- ½ cup full-fat mayo
- ½ teaspoon fresh lemon juice
- 1 tablespoon fresh thyme leaves
- ½ teaspoon freshly cracked black pepper
- 1 lb ground beef 80/20 chuck
- Kosher salt
- 2 to 3 teaspoons yellow mustard classic, not Dijon
- Freshly cracked black pepper
- 4 slices Gruyère cheese
- 4 soft burger buns brioche or potato
- 2 cups arugula
- Neutral oil or beef tallow for the griddle
Instructions
- Melt the butter in a wide skillet over medium-low heat.
- Add the sliced onions and kosher salt, stirring to coat evenly.
- Cook the onions for 45 to 60 minutes, stirring occasionally, until they are deeply browned and jammy.
- Add Worcestershire sauce and beef broth to the onions; simmer until thick and glossy, about 3 to 5 minutes.
- Finish with freshly cracked black pepper and set aside or refrigerate for up to 3 days.
Notes
Feel free to adjust the sweetness of the onions by adding the optional sugar.
For extra flavor, consider adding more herbs such as rosemary or oregano.
These burgers pair wonderfully with a light salad.
Nutrition
- Serving Size: 1 burger
- Calories: 650
- Sugar: 3g
- Sodium: 1150mg
- Fat: 44g
- Saturated Fat: 18g
- Unsaturated Fat: 26g
- Trans Fat: 1g
- Carbohydrates: 33g
- Fiber: 2g
- Protein: 31g
- Cholesterol: 120mg
Nutritional information is an estimate. The nutritional values for your final dish may vary based on measuring differences and products used.