Grilled Roast Beef2018-01-11
Mash first 3 ingredients in small bowl until almost smooth. Place bread on work surface and spread mixture on 1 side of each slice. Top each of 4 bread slices with 1/4 of beef, then onion and arugula. Season with pepper. Top with remaining bread, cheese side down. Melt butter in heavy large skillet over medium-high heat. Add sandwiches and cook until golden, about 2 minutes per side. Serve hot.