SpIn a large nonstick skillet, heat 1/8 inch of oil until shimmering. Spread 1/4 cup of the shrimp mousse on each slice of bread and sprinkle with sesame seeds. In batches, add the bread to the skillet, mousse side down, and cook over moderate heat until golden brown, about 2 minutes. Using a spatula, turn the toasts and cook until golden brown, about 1 minute. Transfer the toasts to paper towels to drain. Cut the toasts into quarters on the diagonal. Sprinkle the remaining 2 tablespoons of scallions on top and serve.