Pastrami, Caramelized Onion, and Gruyère Sandwich

Ingredients

• 4 tablespoons unsalted butter
• 2 onions medium yellow or Walla Walla, cut into 1/8-inch slices
• 1 teaspoon chopped fresh thyme
• 1/4 teaspoon crushed red pepper flakes optional
• kosher salt to taste
• 1 large egg yolks
• 1/2 teaspoon chopped garlic finely
• 1 1/2 teaspoons lemon juice freshly squeezed
• 1 tablespoon Dijon mustard
• 1/2 cup canola oil
• kosher salt to taste
• 4 rolls pretzel, or other sandwich rolls
• 2 tablespoons unsalted butter at room temperature
• 14 ounces pastrami good-quality pepper-crusted
• 4 ounces Gruyere cheese thinly sliced

Nutrition

• Calories : 800 calories
• Carbohydrate : 25 grams
• Cholesterol : 195 milligrams
• Fat : 63 grams
• Fiber : 4 grams
• Protein : 36 grams
• SaturatedFat : 22 grams
• Sodium : 1560 milligrams
• Sugar : 5 grams