Put the whole unpeeled lemon in a saucepan, cover with water, and boil until soft; change the water for fresh water 2-3 times during cooking to remove the bitterness (about 30-40 minutes, until easily pierced with a fork).
Cut the softened lemon in half, remove the seeds, then pass the flesh together with the peel through a sieve to make a purée.
Beat the lemon purée with the sugar and the egg yolks until fluffy.
Sprinkle in the fine semolina, and mix in.
Whip the 8 egg whites into a stiff foam, and fold gently into the lemon base.
Pour into a buttered, floured mold, cover, and steam in a boiling water bath for about 1 hour.
Then transfer to a heatproof dish (or steam directly in one), and bake in an oven at 180 °C for a further 45 minutes, until the top is golden-brown.
Serve warm.
Based on: Malatinszky Fanny szakácskönyve (a classic Hungarian cookbook), modernised. Calories and protein are estimated.