Heat oven to 400°F. Wrap outside of 9- or 10-inch springform pan with aluminum foil. Lightly grease inside of pan.
Combine flour and 1/4 cup sugar in bowl. Cut in butter with pastry blender or fork until mixture resembles coarse crumbs; stir in milk until moistened.
Press crust mixture onto bottom and 1 inch up sides of prepared pan. Bake 15 minutes; remove from oven. Cool to room temperature.
Reduce oven temperature to 325°F.
Combine 1/3 cup sugar, water and cornstarch in 2-quart saucepan. Stir in strawberries and rhubarb. Cook over medium heat, stirring constantly, 5-7 minutes or until mixture comes to a full boil. Continue cooking, stirring constantly, 2-3 minutes or until thickened; remove from heat. Cool to room temperature.
Place cream cheese, 1 cup sugar and lemon zest in bowl; beat at medium speed until well mixed. Continue beating, adding 1 egg at a time and scraping bowl often, until just mixed.
Spoon half of cheesecake mixture over cooled crust. Spoon half of filling over cheesecake mixture; swirl with knife. Top with remaining cheesecake mixture. Spoon remaining filling over cheesecake; swirl with knife.
Place cheesecake onto center rack of oven. Place pan of warm water on rack below cheesecake to prevent cracking. Bake 60-70 minutes or until center is just set. (If browning too quickly, loosely cover with aluminum foil.)
Turn off oven; open oven door 4 inches. Let cheesecake stand in oven 30 minutes; remove from oven.
Loosen sides of cheesecake from pan by running knife around inside of pan. Cool in pan 2 hours. Cover; refrigerate 8 hours or overnight. Remove sides of pan. Store refrigerated.
*Substitute frozen strawberries, thawed, well-drained.
**Substitute frozen rhubarb, thawed, well-drained.