When is a yam not a yam? Surprisingly (or maybe not), when it’s a taro or a sweet potato.
Yam chiffon cake (also known as Taro chiffon cake) is a somewhat confusing misnomer here in NZ. The NZ yam (a small red or orange tuber Oxalis tuberosa) is not the same as the Asian yam. And to make matters worse, what we call ‘yam’ in Asia can be one of several tubers. There is the purple yam (Dioscorea alata) which is the tuber commonly used in making Filipino cakes; and taro (white fleshed Colocasia esculenta, known as ubi keladi in Malay) which is used to make kuihs, bubur cha cha, etc. Plus we have a very purple sweet potato (Ipomoea batatas), which is also sometimes known as yam.
Yam (or taro) chiffon cake is typically lavender in colour, so it’s by default, it’s not the white taro. I went around the various Asian supermarkets in Auckland to see what I could find. In Dan Hua Supermarket (Cnr Torrens St and Ti Rakau Dr, East Tamaki) I found frozen purple ‘sweet potato’. And at Lim’s Orchard (Apirana Ave, Glen Innes), I found frozen grated purple yam. Frozen and fresh taro can be found at most Asian supermarkets.
The yam paste was purchased in Malaysia.
This recipe (slightly modified) comes from the vastly talented Aunty Yochana.
Egg yolk mixture:
6 egg yolks
150 gm frozen grated yam (defrost then microwave on high for 1½ minutes, mash well)
150 gm coconut milk
¼ tsp salt
60 ml vegetable oil (I used rice bran oil)
1 tsp yam paste
Mixed red and blue food colouring to make purple
50 gm castor sugar
180 gm self-raising flour
Egg white mixture:
6 egg white
½ tsp cream of tartar
100gm castor sugar
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 175°C for 50 mins until done
Invert onto cooling rack and leave to cool for ~2 hours. Remove from pan and serve. This wasn’t quite the purple colour I was hoping for, and the yam taste was quite subtle. I will give the frozen sweet potato a go next, and see if that will give me something more akin to the lavender colour and ‘ubi’ taste.