Classic Beef Burgers | Williams Sonoma

Ingredients

• 3/4 lb. ground beef chuck  
• 3/4 lb. ground beef sirloin 
• 1 tsp. sea salt  
• 1/2 tsp. freshly ground pepper 
• 1/2 cup mayonnaise  
• 1/2 tsp. fresh lemon juice  
• 1/4 tsp. finely chopped fresh thyme 
• 1/4 tsp. snipped fresh chives 
• 1/4 tsp. finely chopped fresh basil 
• Sea salt and freshly ground pepper, to taste 
• 4 brioche buns, split 
• 2 heirloom tomatoes, sliced 1/4 inch thick 
• 2 avocados, peeled, pitted and sliced 
• 4 Boston lettuce leaves  
• 4 thin red onion slices (optional) 
• 1 focaccia bread slab, about 6 inches square 
• 2 Maui onions, sliced 1/2 inch thick 
• 1/4 cup olive oil  
• 1/2 lb. Gorgonzola cheese  
• 4 slices Vermont cheddar cheese  
• 1/2 cup barbecue sauce  
• 4 Kaiser rolls, split 
• 8 bacon slices, cooked