1. Combine the shrimp and scallions, white and green parts, in a food processor and process until they form a paste. Transfer to a bowl and stir in the ginger, soy sauce, sugar, sesame oil, and enough egg white to bind the mixture together. Season with the pepper.

2. Spread the bread thickly with the shrimp paste. Cut each slice into four triangles. Sprinkle the sesame seeds evenly over the top.

3. Pour enough oil into a deep-fryer or skillet to come halfway up the sides, and heat to 350°F (180°C). In batches, add the toasts, shrimp sides down, and deep-fry for 2 minutes, until the shrimp paste is puffed. Carefully turn them over and deep-fry until the toasts are crisp and golden brown.

4. Using a slotted spoon, transfer the toasts to paper towels and drain briefly. Serve hot, garnished with coriander.