Preheat oven to 350°F Butter eight 1/2-cup ramekins or custard cups. Place dishes in large roasting pan.
Beat 1/2 cup sugar, butter and lemon zest until well combined. Add egg yolks, one at a time, beating well after each addition. Beat in flour and ground ginger. Add lemon juice and beat to combine. Gradually add yogurt and crystallized ginger.
Using clean dry beaters and a clean dry bowl, beating egg whites until soft peaks form. Add remaining 1/2 cup sugar and beat until stiff but not dry peaks form. Fold whites into yolk mixture in 3 additions.
Divide mixture among prepared dishes. Pour enough hot water into roasting pan to come halfway up side of ramekins, approximately 3 cups.
Bake in preheated oven 25 minutes until pudding cakes are puffed and firm to the touch. Remove dishes from roasting pan and cool on wire rack. Sprinkle wirh icing sugar before serving.