For pears: Cut lemon in half and squeeze juice into large bowl of cold water.
Peel pears; remove blossom end with small melon bailer, but leave core and stem intact.
Immediately plunge into water to retain color.
Combine sugar, water, wine, ginger and salt in large nonaluminum Dutch oven.
Cover and bring to boil, stirring several times to make sure sugar is completely dissolved.
Reduce heat to low and arrange 10 pears standing upright in bottom of pan.
Cover and poach gently until pears are tender, about 30 minutes.
Remove with slotted spoon and transfer to dish large enough to hold all pears in single layer.
Poach remaining pears and add to dish.
Strain all but 2 cups poaching syrup over pears.
Combine ginger in sieve with 2 cups syrup in 1 1/2- to 2-quart saucepan, cover and set aside for ginger topping.
Let pears cool to room temperature; cover; refrigerate overnight.
For ginger cream: Combine cream with 1/2 cup sugar in 2-quart saucepan and heat until glossy film forms on top; do not boil.
Let cool slightly.
Beat egg yolks with remaining 1/2 cup sugar, ginger and salt in large bowl until light and fluffy.
Begin adding cream a few drops at a time and beat well, then gradually add remainder.
Return mixture to saucepan and cook over medium heat until custard is thick enough to coat metal spoon.
Remove from heat and stir in liqueur.
Let cool.
Beat egg whites until stiff but not dry.
Stir about 1/3 into cooled yolk mixture to lighten custard.
Gently fold in remainder.
Cover and chill overnight (or process in ice cream maker).
For topping: Bring reserved poaching syrup to boil over medium-high heat.
Reduce heat and simmer, shaking pan occasionally, until syrup is thickened, about 30 minutes.