Bacon and Egg Sandwiches with Pickled Spring Onions

INGREDIENTS

• 4 large eggs
• 1/4 cup mayonnaise
• 2 teaspoons sugar
• 1 teaspoon kosher salt
• 2 tablespoons pure maple syrup
• 2 tablespoons unsalted butter
• 8 slices white sandwich bread, such as Pullman
• 1/4 cup apple cider vinegar
• 4 spring onions or 6 scallions, whites only, thinly sliced
• 1 cup arugula leaves
• Kosher salt, ground pepper
• 1 tablespoon Sriracha
• 12 slices thick-cut bacon