Coat a large nonstick skillet with cooking spray. Place over medium heat until hot. Add cabbage & onion; cover & cook 5 min.
Combine cabbage mixture, apples & dates in a large bowl. Combine sour cream & mustard; stir well. Add to cabbage mixture; stir well & set aside.
Working with 1 phyllo sheet at a time, spray each sheet with cooking spray; placing one on top of the other. Spoon cabbage mixture lengthwise down one-third of phyllo stack, leaving a 1 inch border on longest side & a 3/4 inch border on shorter sides. Starting with the longest side, roll up jelly roll fashion, & place, seam side down, diagonally on a 15 x 10 x 2 inch jelly roll pan coated with cooking spray; tuck ends under. Brush with margarine. Diagonally cut 1/4 inch deep slashes about 2 inches apart across top. Bake at 400 f. For 45 min. Let stand 10 min. Before serving. Good served with pork.