Step 1

Set a round wire rack in bottom of a large stockpot. Set a 5-cup pudding basin or ovenproof bowl (or two 3-cup basins) on rack. Fill pot with enough water to come about three-quarters of the way up sides of basin. Remove basin; dry, and butter inside. Set aside. Cover pot, and bring to a boil.

Step 2

Butter a 10-inch round of parchment paper; set aside. Whisk together flour, baking powder, and salt in a large bowl. Using a pastry blender or your fingers, cut in butter until pieces are no larger than small peas. Stir in sugar, lemon zest, and currants. Stir in lemon juice, then eggs and milk; stir until combined.

Step 3

Transfer batter to prepared basin. Place parchment round, buttered side down, over basin. Make a pleat in center of parchment. Cover with an 11-inch round of foil. Make a pleat in center of foil to allow room for pudding to expand. Cut a piece of kitchen twine about 7 feet long. Wrap twine twice around basin over foil, just below lip. Knot to secure. Tie loose ends to twine on other side of basin, creating a handle.

Step 4

Carefully lower pudding into boiling water, and cover pot. Return to a boil; reduce to a simmer, and steam until an instant-read thermometer inserted into center of pudding registers 180 degrees, about 2 hours, adding boiling water occasionally to maintain level.

Step 5

Transfer pudding to a wire rack. Let cool 10 minutes. Run a knife around edge of bowl to loosen; invert pudding onto a serving plate. Serve warm, with creme anglaise if desired.