In medium bowl mix crumbs and margarine. Press onto bottom and 2" up sides of lightly greased 9" springform pan; set aside.
To make filling, in mixer bowl beat ricotta cheese until smooth. Add ¾ cup of the sugar, the flour, egg yolks, lemon peel and vanilla; mix well. Stir in sour cream substitute to blend thoroughly. In another bowl, beat egg whites until stiff but not dry, fold into cheese mixture. Pour into prepared crust, smooth top.
Bake 1 hour. Turn off oven, cool in oven 1 hour with door ajar. Remove from oven, chill thoroughly.
Meanwhile, to make sauce, in blender or food processor puree 2 baskets of the strawberries with the remaining ¼ cup sugar and the lemon juice; strain sauce to remove seeds. Cover and chill. To complete cake, halve remaining strawberries, arrange on top of cake. Brush strawberries with jelly. Cut cake into wedges; serve with sauce.