Heat oven to 375°F. In 10-inch skillet, mix cooked beef and bell pepper. Heat over medium-high heat, stirring occasionally, until hot. Stir in ketchup, brown sugar, mustard and salt. Set aside. Separate dough into 4 rectangles. Place on ungreased cookie sheet. Press each to 8x5 inches, firmly pressing perforations to seal.
Divide beef mixture evenly among rectangles. Bring ends up over filling, overlapping about 1 inch. Press edges with fork to seal.
Bake 13 to 15 minutes or until golden brown. Immediately remove from cookie sheet. Serve warm.