Classic Cheeseburgers

Name: Classic Cheeseburgers
Cuisine: American
Ingredients: 1 pound ground chuck (80% lean); 1 pound ground sirloin; Sea salt; Freshly cracked black pepper; 4 or 8 brioche burger buns; 1/3 cup yellow mustard; 1 tablespoon butter; 8 slices American cheese; 4 to 8 (1/4-inch-thick) tomato slices; 4 to 8 (1/4-inch-thick) red onion slices; 8 pickle slices; 8 burger-size lettuce leaves; Spicy Herb Homemade Mayo, for serving (see Note); 2 tablespoons vegetable oil; 1 cup finely diced red onion; 2 garlic cloves, minced; 1 tablespoon tomato paste; 1 teaspoon curry powder; 1/2 teaspoon smoked paprika; 1/4 teaspoon cayenne pepper; 1/4 teaspoon ground cinnamon; 1/4 teaspoon ground allspice; 1 (28-ounce) can diced tomatoes; 1/2 cup pure maple syrup; 1/2 cup apple cider vinegar; 1 teaspoon kosher salt; 1/2 teaspoon freshly cracked black pepper; 5 cups all-purpose flour, plus more for dusting; 1 tablespoon active dry yeast; 3 tablespoons sugar