Ingredients

• 1 1/2 tablespoons olive oil
• 2 8- to 10-ounce red onions, cut into 1/3-inch-thick rounds
• 3 1/2 tablespoons red wine vinegar
• 6 cups trimmed large arugula leaves (about 4 ounces), divided
• 3/4 cup mayonnaise
• 8 1/3-inch-thick slices seeded wheat bread (such as La Brea Bakery) or four ciabatta rolls, cut horizontally in half
• 12 ounces thinly sliced smoked turkey
• 3/4 cup coarsely crumbled blue cheese (such as Maytag; about 3 ounces)

Instructions

1. Heat oil in large nonstick skillet over medium-high heat. Add onions and sauté until soft and lightly browned, breaking up onion rings, about 8 minutes. Remove from heat; stir in vinegar and season to taste with salt and pepper.
2. Chop enough arugula to measure 1 cup; place in medium bowl. Mix in mayonnaise. Season with salt and pepper. Spread about 11/2 tablespoons arugula mayonnaise over each cut side of bread. Divide turkey slices among 4 bread slices. Top with crumbled blue cheese, dividing equally. Top with red onions, then whole arugula leaves and bread.