Cajun Burgers with Spicy Rémoulade

Ingredients

• 1 1/2 pounds beef chuck, cut into 1-inch cubes
• 8 ounces Creole andouille sausage, cut into 1/2-inch cubes
• 1 cup mayonnaise
• 1 tablespoon ketchup
• 1 tablespoon hot sauce, such as Tabasco
• 2 tablespoons mustard
• 1 tablespoon chopped flat-leaf parsley, leaves and tender stems
• 1 tablespoon fresh juice from 1 lemon
• 1 teaspoon cayenne pepper
• 2 teaspoons jarred horseradish
• 2 medium cloves garlic
• Kosher salt and freshly ground black pepper
• 3 stalks celery, thinly sliced lengthwise with a vegetable peeler
• 1/2 white onion, thinly sliced crosswise
• 1 large red bell pepper, thinly sliced
• Vegetable oil, for brushing
• 6 hamburger buns
• 8 ounces blue cheese, crumbled

Directions

1. Lay the beef out in one even layer on a rimmed baking sheet or a large plate. Put it in the freezer until the edges are just starting to firm up, about 20 minutes. In batches, add 1/3 of the beef to a food processor and pulse until it is very coarsely chopped, about 10 pulses. Add 1/3 of the andouille and pulse again until the sausage is evenly worked through and the mixture is finely chopped, about 10 more short pulses. Do the same with the remaining beef and andouille.
2. Shape the meat gently into 6 patties, making each one about 1/2 inch wider than the hamburger buns. Press your thumb into the middle of each patty to make a shallow indentation. Place the patties on a baking sheet and refrigerate them until it is time to grill.
3. Add the mayonnaise, ketchup, hot sauce, mustard, parsley, lemon juice, cayenne pepper, horseradish, and garlic to a food processor. Blend until smooth, then season with salt and pepper. Put the rémoulade aside.
4. Put the celery strips in a bowl filled with ice water, then refrigerate them until you are ready to build the burgers.
5. Light one chimney full of charcoal. Once the coals are glowing and coated with gray ash, dump them out and arrange them evenly over half of the coal grate. For a gas grill, turn half the burners to high heat instead. Put the cooking grate in position, close the grill, and let it heat for 5 minutes. Scrape the grate clean and oil it.
6. Brush the onion and bell pepper with oil. Grill them until they are tender and lightly charred, about 4 minutes per side. Move them off the grill and set them aside.
7. Season the patties with salt and pepper. Set the burgers right over the hot coals, cover the grill with the vents open, and cook, turning now and then, until an instant-read thermometer reads 125 degrees F for medium-rare or 135 degrees F for medium, about 6 minutes. Move the burgers to a large plate.
8. Toast the buns near the center of the grill until they are warm and golden brown.
9. Build each burger with the bottom bun first, then a dollop of rémoulade, grilled onions and peppers, a patty, another dollop of rémoulade, celery, blue cheese, and the top bun. Serve right away.