Preheat oven to 350.  Brush sides and rim of pie shell with beaten egg white; prick crtust and sides with tines of a fork.  Bake at 350 for 10-12 minutes until light and golden.  Do not overcook.  Let crust cool.  Fill crust with tomatoes.  Mix mayonnaise with 3 tablespoons cheese, dry mustard, lemon juice, basil, pepper, and garlic powder; spoon over tomatoes.  Top with remaining cheese.  Bake at 350 for 20 minutes or until top is golden brown.  Serves 6-8 as a vegetable or 4-6 as a meat substitute.