In a large skillet, cook onion and green pepper in sale dressing just until tender. Stir in mustard, remove from heat. Set aside.
Grease cookie sheet. In large bowl, combine flour mixture with yeast from foil packet. Stir in hot water, 2 Tbsp oil and egg until dough pulls away from sides of bowl. Turn dough out onto floured surface. With greased or floured hands, shape dough into a ball. Knead dough for 5 min until smooth. Sprinkle additional flour over surface to reduce stickiness. Cover with large bowl, let rest 5 min.
On lightly floured surface, roll dough to 16x14" rectangle. Arrange ham, salami and Swiss cheese lengthwise over 1/2 of dough, overlapping slices; sprinkle with cheddar. Spread onion mixture over meats and cheeses. Fold remaining 1/2 of dough over filling Pinch edges to seal; tuck ends under. Place on greased cookie sheet. Cover loosely with greased plastic wrap and cloth towel. Let rise in warm place 15 min.
Heat oven to 400F. Uncover dough. Brush with 1 Tbsp oil, sprinkle with poppy seed. Bake at 400F for 15-20min or until golden brown. Let stand 15-30 min before serving. Cut in half lengthwise, then make 10 crosswise cuts forming 20 slices.
Nutrition Info Per Serving: Calories 353 Total Fat 22 g Cholesterol 57 mg Sodium 735 mg Potassium 124 mg Total Carbohydrate 29 g Dietary Fiber 1 g Sugars 12 g Protein 11 g