I gave version 1 a barely passable ‘C’ grade as it tasted mostly egg-y and sweet and required the addition of a considerable amount of food colouring to obtain the lavender hue. Younger bro actually asked me what flavour it was. Sacrilege! I decided to use purple sweet potato to see if it would make the grade. These can be found in the frozen section at my local Asian supermarket, Lim’s Orchard (Apirana Ave, Glen Innes).
This version definitely tasted more ‘ubi’ or starchy. I found that the flavour developed better on the second day. I used the same recipe as before, and due to the vibrant purple colour of the sweet potato, I decided to omit the extra food colouring.
Egg yolk mixture:
6 egg yolks
150 gm. Purple sweet potato (steamed and pureed)
150 gm coconut milk
¼ tsp salt
60 ml vegetable oil (I used rice bran oil)
1 tsp yam paste
50 gm castor sugar
180 gm self-raising flour
Egg white mixture:
6 egg white
½ tsp cream of tartar
100gm castor sugar
To prepare the sweet potato, I defrosted the potato in the fridge overnight (or you could use the defrost setting on the microwave), then peeled and steamed the thick slices for 15 minutes. The slices get quite friable after steaming and started to break apart. I mashed and pureed it with a stick blender. I recommend to press it through a sieve as well, as it is difficult to get a lump-free batter.
Add all the egg yolk mixture ingredients together and mix until smooth using a whisk.
Add cream of tartar to the egg whites. Whisk mixture on high, gradually adding in sugar, until stiff peaks form.
Fold the egg white into the egg yolk mixture until well blended. Scrap the bottom of the bowl to ensure the batter is evenly mixed.
Pour into a 22cm uncoated tube pan.
Bake at 175C for 50 mins until done.
Remove from oven, invert onto cooling rack and leave to cool for ~2 hours. Remove from pan and serve.