1Combine sugar, cornstarch, and salt in top of a double boiler over simmering water; stir well to prevent clumps. Gradually stir in 5 cups water. Cook, stirring frequently, until mixture is thickened to gravy consistency, 5 to 7 minutes. Remove from heat.
2Beat eggs in a bowl until light and foamy. Pour in 1 cup of sugar mixture gradually, whisking vigorously to avoid curdling eggs. Whisk egg mixture into remaining sugar mixture gradually; return to double boiler. Cook, whisking constantly, until thickened to pudding consistency, 6 to 8 minutes. Whisk lemon juice and butter into pudding gradually. Cool in the refrigerator, 30 minutes to 1 hour.
Footnotes
Cook's Notes:
Margarine can be substituted for the butter, if desired.
Pudding will thicken more as it cools in the refrigerator.
Tip
Aluminum foil helps keep food moist, ensures it cooks evenly, keeps leftovers fresh, and makes clean-up easy.