Chipotle Salmon Burger

In a medium bowl, whisk together the mayonnaise, lime juice, and soy sauce. Add the bell pepper, onion, and chopped chipotle peppers, and stir until well combined. Fold in the panko, flaxseed, and beaten egg. Gently fold in the salmon. Divide the mixture into six equal parts and, using clean hands, shape each into a ball. Pat each ball into 2 1/2-inch-wide and 3/4-inch-thick burger patties. Place the patties into an airtight container and cover. Heat a medium grill pan or cast- iron skillet over medium- high heat. Add the olive oil, reduce the heat to medium, and cook the patties, in batches, until golden brown, 2 to 3 minutes. Gently turn them over and brown the opposite sides for an additional 2 to 3 minutes. Transfer the cooked patties to a paper towel-lined plate while you prepare the sauce. In a small bowl, whisk together the yogurt, chives, and Worcestershire sauce. To serve, place each burger on a toasted bun, smear on a dollop of the sauce, and layer on the kale and thinly sliced red onion.