Shred cabbage (be sure it is a firm, crisp head) very thin. Mix in peppers and soak in ice water until very crisp. Then drain and pour over it cooked dressing made by mixing 1 teaspoon mustard, 1-1/2 tablespoons sugar, 1 tablespoon flour and 1-1/2 teaspoons salt and adding to 3 whole eggs, beaten. Stir in 1 cup milk and cook in top of double boiler. Slowly add 1 cup vinegar as mixture cooks. Keep stirring. When mixture starts to get thick, add 1-1/2 tablespoons butter and 1-1/2 teaspoons celery seed. Remove from heat when thick and chill before adding to cabbage-pepper mixture.