French Dip Burger

Ingredients

Here are the following ingredients:

• 5 lb (2.2 kg) Ground Beef (Medium)
• 2 oz (60 g) butter
• 2 lb (1 kg) thinly sliced onion, about 8 cups (2 L)
• 2 tbsp (30 mL) dried thyme leaves
• 2 tsp (10 mL) kosher salt (approx)
• 1 tsp (5 mL) freshly ground black pepper (approx)
• ¼ cup (60 mL) apple cider vinegar
• 8 cups (2 L) beef stock (no salt added)
• 1¼ cups (300 mL) mayonnaise
• ¼ cup (60 mL) prepared creamy horseradish

Service

• 16 slices Gruyère cheese, about 8 oz (250 g)
• 16 brioche or pretzel buns, split and lightly toasted
• 2½ oz (75 g) arugula, about 4 cups (1 L)

Preparation

1. Form beef into 16 (5 oz/150 g) burger patties, about ½-inch (1 cm) thick. Cover and refrigerate.
2. Melt butter in large skillet over medium heat. Add onions, thyme, salt and pepper. Cook, stirring often and reducing heat if needed, for 45 to 60 minutes or until tender and caramelized. Pour in vinegar; cook until almost evaporated.
3. Remove all but 1 cup (250 mL) onions from skillet and reserve for topping burger. Cool, cover and refrigerate.
4. Pour beef stock into skillet over remaining onions; bring to a boil. Simmer until reduced to jus-like consistency. Season with salt and pepper. Cool, cover and refrigerate or hold for service.
5. Stir together mayonnaise and horseradish. Cover and refrigerate.

Service

1. Season beef patty with salt and pepper. Grill or sear on flat top, turning as needed, until a digital instant-read thermometer inserted sideways into centre of patty reads at least 160°F (71°C). 
2. Top with cheese and 1 tbsp (15 mL) caramelized onions. Cook until cheese melts.
3. Spread 4 tsp (20 mL) horseradish mayo on bottom bun. Top with burger, arugula and top bun. Serve with ⅓ cup (75 mL) jus for dipping. 

Beef Cuts