I would use applesauce instead of some of the water and oil, and shred some potatoes super thin and add them as well. Do you mean fresh fruit, or citron? If fresh, it's going to add a lot of water content, so you have to adjust for that as well. The potato will absorb some, so you have to adjust for that as well. It's all very scientific, my dear chap.

Maybe use sweet potato instead of regular potato? Might blend better with the spice and fruit. Not sure how to execute, though... maybe cooked mashed sweet potato in the batter?

this wouldn't be "light," but you could use potato for crust; make a sort of gallette as the crust.
this might play well as a sweet/savoury combo with the fruit.
i guess this is heading more into pie or flan territory, though.

You could make a vegan carrot cake, substituting half the carrot with half grated sweet potato.

250g (8oz) wholemeal flour
1 tblsp. ground cinnamon
1 tblsp. grated nutmeg
2 tsp. baking powder
100g (4oz) margarine
100g (4oz) light muscovado sugar
100g (4oz) maple syrup
250g (8oz) carrots, finely grated
50g (2oz) walnuts, chopped
50g (2oz) sultanas

Method
1. Mix together flour, nutmeg, cinnamon and baking powder. Melt the margarine with the sugar and maple syrup, then stir into the flour.

2. Add grated carrots, walnuts and sultanas, mix well.

3. Spoon into a greased, base lined 1 lb loaf tin, bake Gas 3, 160C for one hour and 15 minutes.

4. Leave to cool in the tin for ten minutes, then cool on a wire rack.


Then for the filling/icing, try this:

Beat mashed potato, icing sugar, soya milk and vegan margarine together with zest and juice of lemon/orange and a little vanilla extract until you get the consistency and flavour you want. I suspect you'd need a fairly high margarine/sugar ratio to potato, to prevent it from being too starchy.

I'll de-lurk for this one. Just some ideas:
Would you consider incorporating the potato aspect into a sort of marzipan cream (mashed potatoes, adding sugar, powdered almonds, a bit of soya/rice milk and *good* almond extract) and for the cake, maybe a gingerbread?
I think Pip's & iconomy's suggestions for applesauce and sweet potato would work really well in a gingerbread type cake, especially with some preserved ginger thrown in. It wouldn't be 'light' though.
Maybe for the fruit: orange segments on top? They'll stick to a whipped marzipan mixture so long as they're not wet. Almond, ginger and oranges. Just a suggestion.

Then again, you could also just use (some) potato flour instead of wheat flour for the actual cake.

Man, it's bright in here. ~goes back into the shadows~

um, err, lesson #1 about posting: pre-read all posts by hitting refresh *before* posting, especially if you've held off submitting while your account is being activated.

in an attempt to save face: sure, just follow essexjean's recipe...

(now I'll really go back into the shadows and let the grown-ups play)

stay and play, stay and play! we only look like grownups.

How can I be a grown-up? I'm only 4ft 11!

I'm so befuzzled. Potato? In cake?

Potato by itself is a fairly flavourless starch, usually enhanced in cooking by the addition of seasonings or by frying. So, provided the proportions are right, it would go well in a cake. I'd think a floury potato such as a King Edward or a Maris Piper would be better than a waxier variety. I would also not recommend new potatoes in cakes ;-)

That makes complete sense. It still feels weird to me, though. Then again, I only recently accepted that cheesecake actually contains cheese, so I'm hardly a good judge of ingredients.

i think very thinly slices oiled potatoes on the edges and sides might complement a very richly chocolatey cake, maybe with strawberries or raspberries, apricots even.
i'm going to variated on your crazy cake.

extra d, oops

Hi Kai, Hi Kai!

I like saying that.