In a medium bowl, combine diced chicken, soy sauce, vinegar, sesame oil, chili paste with garlic, 1 teaspoon dry mustard, scallions, red pepper, and water chestnuts. Mix well and set aside. Turn half the bread cubes into a buttered 11 x 7 baking dish. Sprinkle with half the cheese. Distribute half the chicken mixture over cheese. Cover with remaining bread cubes and remaining 0.75 teaspoon dry mustard until blended. Pour evenly over casserole. Cover with plastic wrap. Refrigerate several hours, or overnight.
Preheat oven to 180ºC . Bake, uncovered 40 to 45 minutes, until top is golden and center is set. Let cool 5 minutes, then cut into squares or rectangles to serve.
From the MM database of Judi M. Phelps. jphelps@slip.net or jphelps@best.com