Grease 23 cm springform pan; sprinkle with graham cracker crumbs, tilting pan to coat the sides. Into a large bowl, mash cottage cheese through sieve; add cream cheese. Beat on high setting with electric mixer until well blended. Beat in sugar, then 2 eggs. Reduce speed to slow. Beat in cornstarch, lemon juice and vanilla, then margarine or butter and sour cream until smooth. Pour into prepared pan. Bake in 325 deg F oven for 70 minutes or until firm around the edge. Turn oven off. Let cake stand in oven for 2 hours. Take out and chill. Remove side of pan. If desired, cover with Strawberry glaze. Freezes well. STRAWBERRY GLAZE Mix cornstarch, water and light corn syrup until smooth. Add strawberries. Bring to a boil for 1 minute. Strain. Stir in lemon juice and, if desired, a drop of red food coloring. Cool slightly, then cover top with glaze.