Make the shrimp paste: Combine the shrimp, egg white, green onion, cornstarch, rice wine, ginger, salt, sesame oil and pepper in the workbowl of a food processor. Process until the mixture is smooth, stopping once or twice to scrape down the sides.
Trim the crusts from the bread. Brush 1 side of 1 of the bread slices with the beaten egg and lightly press the nori sheet over the egg. Place the bread on a cutting board, nori side down, and trim any of the nori that extends past the edge of the bread. Spread about 1/3 of the shrimp paste over the bare side of the bread, mounding it slightly in the center. Sprinkle 1/3 of the black sesame seeds over the shrimp paste. With a chef's knife, cut each slice into 4 triangles. Repeat with the remaining ingredients.
Pour enough oil into a wok or a high-sided frying pan to come to a depth of 2 inches and heat over medium heat to 350 degrees F.
Slide 3 or 4 toasts, shrimp side down, into the oil. Cook for about 1 minute, turn over and continue cooking until edges are golden brown, about 1 minute longer. Scoop the toasts from the oil with a slotted spoon and drain on paper towels. Repeat with remaining shrimp toasts. Serve warm.
Recipe courtesy Martin Yan, Martin Yan's Chinatown Cooking, William Morrow, 2002