Preheat the oven to 375F. Coat a nonstick baking pan with cooking spray. Rinse the fillets with cold water and pat dry. In a wide bowl, beat the egg white, water, and salt with a fork.
One at a time, dip the fillets into the egg white mixture, shaking off the excess. Place on the prepared pan. Sprinkle the tops and sides of the fillets with the sesame seeds. Bake for 15 minutes, or until the fillets are opaque in the center.
Meanwhile, in a bowl, combine the salsa and yogurt. Serve over the fillets and sprinkle with cilantro.
Note: To toast sesame seeds, place them in a dry medium skillet over medium-high heat. Cook, stirring, for about 2 minutes, or until the seeds are golden and start to pop. Once cooled, toasted seeds may be stored in the freezer for several months.