Combine the juliènned, parboiled orange and lemon peels with the sugar and water, bring to a boil, and simmer until the liquid is almost entirely reduced, the peels coated with a thick syrup, but remove from the flame before the sugar begins to caramelize.
Pound the almonds and pistachios together in a mortar until well crushed into a coarse purée, add the peels and a bit of sugar, and continue pounding, adding sugar from time to time, until the mixture becomes too stiff to work easily. Continue pounding, alternating additions of white wine and sugar until both are used up. Add the egg yolks and work vigorously, pounding and stirring with the pestle.
Beat the egg whites with the pinch of salt until they stand firmly in peaks, fold a healthy spoonful into the mixture in the mortar, then turn the contents of the mortar into the bowl containing the remaining egg whites, and fold the two gently together.
Pour into a buttered gratin dish and bake at 375°, the dish immersed by half in a larger pan containing hot water, for about 25 minutes, or until the center of the pudding is firm to the touch.
The ingredients (except for the final incorporation of the beaten whites) may be added progressively to one of the “robot-cutter,” “cuisinarts,” or “magimix” mechanisms with extremely rapid and satisfactory results.