Combine sugar and cornstarch in a 2-quart glass measure. Gradually add water and lemon juice, stirring with a wire whisk until blended. Stir in raspberries. Cover with wax paper, and microwave at HIGH 6-1/2 to 7 minutes or until thickened and bubbly, stirring every 2 minutes. Press raspberry mixture through a sieve, reserving 1-1/2 cups juice; discard seeds. Combine reserved raspberry juice and strawberries in a bowl; stir well. Cover and chill. Serve over orange sherbet or angel food cake. Yield: 2-2/3 cups (serving size: 1 tablespoon). Calories 14 (0% from fat), protein 0. 1g, Fat 0g (sat 0g, mono 0g, poly 0g), carb 3.6g, Fiber 0.4g, Chol 0mg, iron 0mg, sodium 0mg, calcium 1mg