Lemon Potato Starch Sponge Cake
A tender vintage lemon sponge with 12 eggs, fresh zest and juice, and potato starch in place of flour, baked in a tube or bundt pan.
Quick Summary
Lemon koh is a light Central European sponge cake built on 12 eggs, fresh lemon zest and juice, and potato starch instead of flour. It takes about 75 minutes, plus cooling, and bakes into a fine, tender crumb with no leavening beyond whipped egg whites.
Historical recipe
Modernised adaptation of an early 20th‑century source. Not independently kitchen-tested by Attic Recipes. Quantities, temperatures, and food safety guidance have been updated for a contemporary kitchen — results may vary and errors may exist. Nutritional values, where provided, are estimates only and have not been laboratory tested. Always follow current food safety guidelines for your region. If you have a health condition, allergy, or dietary requirement, consult a qualified professional before preparing this recipe.
Use of this recipe is entirely at your own risk and subject to ourTerms of Service andPrivacy Policy. Attic Recipes accepts no liability for any adverse outcome.
- Eggs
- Dairy
- Gluten
Additional notes
Note
This cake is high in sugar (about 21g per slice) and made with 12 egg yolks, so it is best enjoyed as an occasional treat, particularly for children, older adults, and anyone monitoring their sugar or cholesterol intake. The cake must be baked through until a skewer comes out clean, which also makes it safe for pregnant women and immunocompromised people.
- 1
Preheat the oven to 170°C (340°F) / 150°C fan. Grease a 3-litre tube or bundt pan thoroughly with 15g soft unsalted butter, getting into every ridge. Dust with 15g plain flour, turn the pan to coat, and tap out the excess.
TipThe batter is voluminous. The pan must hold at least 3 litres and should be no more than three-quarters full. - 2
Finely grate the zest of 2 unwaxed lemons, then squeeze the lemons to get 80ml juice. Separate 12 large eggs, putting the yolks in a large bowl and the whites in a very clean, dry, grease-free bowl.
TipSeparate the eggs while cold, as the yolks are firmer, then let them come to room temperature before beating. Even a trace of yolk in the whites will stop them from whipping to full volume. - 3
Add 250g caster sugar and the lemon zest to the 12 yolks. Beat on medium-high speed until pale, thick and foamy, and the mixture falls from the whisk in a slow ribbon, about 10 minutes with a mixer.
TipTraditional hand-whisking took about 30 minutes. With a mixer, judge by texture, not the clock: the mixture should roughly triple in volume and the sugar should be fully dissolved. - 4
Beat in the 80ml lemon juice. Sift 250g potato starch over the mixture in three additions, folding gently with a spatula after each until no dry streaks remain.
TipThe batter will be thick and slightly stiff at this point. Sifting prevents lumps of starch, which do not break up later. - 5
In the clean bowl, whip the 12 egg whites to stiff, glossy peaks that stand upright when the whisk is lifted, about 5–6 minutes with a mixer.
TipStop as soon as the peaks hold. Overbeaten whites turn grainy and dull and will not fold in smoothly. - 6
Stir about one-third of the whipped whites into the batter to loosen it, then fold in the remaining whites in two additions, cutting down through the centre and lifting from the bottom until no streaks of white remain. Pour into the prepared pan, level the top, and tap the pan once on the counter.
TipFold gently and stop as soon as the batter looks even. Every extra stir knocks out air, and air is the only leavening in this cake. - 7
Bake on the middle rack for 45 minutes, until the cake is deep golden, springs back when lightly pressed, and a skewer inserted into the thickest part comes out clean.
TipDo not open the oven door during the first 30 minutes. If the skewer comes out wet, bake up to 10 minutes longer, covering the top loosely with foil if it is browning too much. A fully baked cake reaches at least 96°C (205°F) in the centre. - 8
Let the cake cool in the pan for 15 minutes. Run a thin knife around the edges and the centre tube, invert onto a wire rack, and cool completely, about 45 minutes, before slicing.
TipA starch-based sponge is fragile while warm. Cutting it too early compresses the crumb and makes it gummy.
Nutrition Informationper 1 slice (approx 90g)
Nutritional values are approximate estimates and may vary based on specific ingredients used, preparation methods, and portion sizes.
Serving Suggestions
Serve at room temperature in thick slices, plain or with a light dusting of icing sugar, alongside tea or coffee. Fresh berries or lightly whipped cream suit it well. Store, covered, at room temperature for up to 2 days.
About This Recipe
Lemon koh is a tall, tender sponge cake lightened entirely by eggs. Twelve yolks are beaten with sugar until thick and foamy, scented with fresh lemon zest and juice, and then combined with potato starch and stiffly whipped egg whites. There is no baking powder, so everything the cake needs to rise comes from the air you beat into it.
Potato starch contains no gluten-forming proteins, so the crumb comes out fine, soft and slightly sandy rather than chewy. The lemon keeps a cake this rich in yolks bright and fresh, with real citrus flavor from both the zest and the juice.
It is a plain cake, baked in a ring mold and served in slices, the kind of thing that sat on the table with coffee or tea and needed no frosting.
Why It Works
Two foams carry the structure. The long beating of yolks and sugar creates a thick, stable foam, and the whipped whites add a second, lighter one. As the cake bakes, the egg proteins set around the trapped air while the potato starch gelatinizes and holds moisture, which is what gives the crumb its softness. Because the starch has no gluten to toughen the batter, the cake stays tender even if you fold slightly more than you meant to.
The lemon juice also loosens the thick yolk mixture, making it easier to fold in the starch and whites without deflating them.
Modern Kitchen Tips
Use a spotlessly clean, dry, grease-free bowl for the whites, and avoid plastic bowls, which can hold traces of fat. Wash and dry the whisk as well.
Sift the potato starch directly over the batter in several additions. It clumps easily, and lumps will not dissolve during baking.
Do not open the oven in the first 30 minutes. A sudden drop in temperature can make a cake that depends on air alone collapse.
Cool the cake completely before slicing, using a serrated knife and a gentle sawing motion. Wrapped well, slices freeze for up to 2 months.
A classic of early 20th century home cooking, preserved and adapted for the modern kitchen.
The Story Behind This Recipe
Historical Context
Cakes lightened entirely by beaten eggs, with potato starch used in place of wheat flour, were part of Central European home baking. Early 20th century recipes for this type of sponge typically beat the yolks and sugar by hand for as long as half an hour, since the volume of the cake depended on it. Home cooks of the period used a tall ring or tube mold, and the traditional approach did not specify the pan size, the oven temperature, or the amount of butter and flour needed to prepare the mold.
Modern Kitchen Adaptation
Oven temperature was not given in the period approach and has been estimated at 170°C (340°F) / 150°C fan, with a skewer test as the real indicator of doneness. Pan size and the amounts of butter and flour for preparing it were also not specified and have been estimated for a 3-litre tube or bundt pan. The lemon juice amount (80ml) is a conversion of the juice of 2 large lemons. 'Fine sugar' is read as caster sugar. Half an hour of hand-whisking is replaced by about 10 minutes with an electric mixer, judged by ribbon stage. Starch is sifted before folding in to avoid lumps. Unwaxed lemons are recommended because the zest is eaten. For a cake free of wheat, dust the pan with potato starch instead of flour; the allergen list reflects the recipe as written. The cake is baked fully through, so there is no raw egg in the finished product.
Images on this site are AI-generated illustrations in a 1930s style; your finished dish may look different.
This recipe is an independent modern adaptation developed from historical sources in the public domain. It is provided for informational and educational purposes only and does not constitute professional dietary, nutritional, or medical advice. Food preparation involves inherent risks. The reader assumes full responsibility for safe food handling, ingredient sourcing, and adherence to current local food safety guidelines. The site operator accepts no liability for outcomes resulting from the preparation or consumption of this recipe.
One recipe.
Every week.
You Might Also Like
More recipes you'll enjoy
Easter Torte with Apricot Jam and Whipped Cream
Five thin semolina sponge layers filled with apricot jam and vanilla whipped cream, topped with piped cream for a light vintage Easter torte.
Meringue Grape Cake Squares
A butter cake base spread with apricot jam, topped with sweetened meringue and grapes, baked until golden and cut into squares.
Classic Jam-Filled Crepes
Thin, delicate egg crepes with very little flour, pan-fried and rolled around jam, finished with vanilla sugar — a simple Central European classic.