Peel and finely grate the ginger. Strain through a fine mesh sieve or cheesecloth to extract the juice. Measure out 1 tablespoon.
Heat the milk in a small saucepan until hot but not boiling, about 170°F. Stir in the sugar.
Add the ginger juice to a heatproof bowl. Pour the hot milk directly over it, then cover with a plate.
Let sit undisturbed for 10 to 15 minutes. Do not stir or move the bowl.
The pudding is set when a spoon can rest on top without sinking. Enjoy warm.
