Pepper Burgers with Spicy Mayo, Caramelized Onions, Blue Cheese and Arugula on Grilled Ciabatta

Ingredients

1/2 cup light mayonnaise
3 tablespoons Dijon mustard
1 1/2 tablespoons prepared white horseradish
3 tablespoons olive oil
6 white onions, sliced
1/2 teaspoon fresh chopped thyme
salt
pepper
1 pound ground sirloin
1 pound ground chuck
3 cloves pressed garlic
1 1/2 teaspoon kosher salt
2 tablespoons coarsely ground black peppercorns
8 ounces top quality crumbled blue cheese
6 ciabatta rolls
4 tablespoons olive oil
1 clove garlic
2 cups arugula

Instructions

Turn on the grill to medium high. Close the grill lid.
Spicy mayo;
Whisk the mayo, mustard and horseradish together. Keep mayo cold, but bring to room temperature just before serving.
Caramelized onions;
Place 3 tablespoons olive oil into a large fireproof skillet.When hot, add the sliced onions and the thyme, add salt and pepper and stir them. Saute about 15 minutes or until they are golden brown, stirring occasionally.
Patties;
Put the ground meat into a large bowl. Distribute the garlic and the salt evenly over the meat and mix gently with your hands. Form 6 patties, handling as little as possible. Liberally sprinkle both sides of patties with the pepper.
Brush the grill with oil. Place patties on the rack and cook about 5 minutes. Flip the patties, only once, for an additional 4-5 minutes. An internal temperature of 160 degrees F. is suggested. During the last 2 minutes of grilling, put a liberal amount of blue cheese onto each patty. Slice the ciabatta and lightly brush the cut sides with oil. Place the cut sides down on the grill and lightly toast.
Assembly;
Spread the mayo on both sides of the ciabatta. Layer the bottom rolls generously with the arugula, then the patties. Top the patties with the caramelized onions. Top off the the other 1/2 ciabatta. Serve and enjoy.