Ingredient note: Rice papers are handy wrappers, commonly used in Vietnamese cooking. You can buy them at Asian markets, large supermarkets or order them through the mail. They keep indefinitely on your pantry shelf.
Toast sesame seeds in a small dry skillet, stirring, over medium heat, until golden and fragrant, 2 to 3 minutes. Stir together soy sauce, scallions, chopped cilantro, vinegar, ginger, sugar and the sesame seeds in a small bowl.
Fill a large bowl with very hot water. Working with one sheet at a time, dip rice papers in water until completely softened, about 10 seconds. Place on a towel to drain. Arrange 3 cilantro sprigs attractively in the center of each rice paper. Season salmon with pepper and place over the cilantro sprigs. Fold the rice paper over the salmon to enclose it.
Heat oil in a large nonstick skillet over medium-high heat. Place the salmon packages in the skillet, seam-side down, and cook for 1 1/2 minutes. Turn and cook for 1 1/2 minutes more. Remove from the heat and let stand, covered, for 2 minutes then serve with the dipping sauce.