Grind the shrimp, ginger, garlic & water chestnuts in meat grinder or food processor. Season w/ salt & pepper. The mixture should be paste-like. Add sherry,egg white & baking soda to the shrimp mixture. Spread it generously over bread slices. Trim edges. Cut each piece of bread diagonally into quarters to form triangles. Form a mound in center of each triangle w/ spread & sprinkle w/ sesame seeds. Heat oil to 300 to 325. Deep-fry shrimp toasts until golden brown on both sides. Drain on paper towels & serve w/ mustard sauce & sweet & sour sauce.