Panko is a Japanese type of bread crumb that is especially light and crunchy, popular with chefs because it doesn’t get soggy. What I love about this way of preparing salmon is that the panko topping seems to hold in the salmon’s moisture while roasting, so the salmon doesn’t get dried out at all. Some honey mustard spread over the top of the fillets provides the “glue” that holds the seasoned panko on to the fillets.