1.In A Small Bowl, Combine The Spinach, Onions And Sour Cream. Spread Into An Ungreased 13-In. X 9-In. X 2-In. Baking Dish. Cut Sole Fillets Into 6-In. X 2-In. Strips; Carefully Roll Up And Secure With Toothpicks. Place Over Spinach Mixture. Sprinkle With Lemon-Pepper. Bake, Uncovered, At 350 Degrees F For 15-20 Minutes Or Until Fish Flakes Easily With A Fork. 2.In A Saucepan, Combine Cornstarch And Water Until Smooth. Gradually Add Tomatoes. Bring To A Boil Over Medium Heat; Cook And Stir For 2 Minutes Or Until Thickened. Discard Toothpicks From Roll-Ups. Spoon Tomato Sauce Over Roll-Ups And Spinach Mixture.