Friday, November 16, 2012

Sweet Potato / Yam and Sweet Soup

This is the season of sweet potatoes (or fàan-syùh 番薯 in Cantonese) and thus the time to make sweet soups with them. Fàan-syùh tòhng-séui* in Cantonese (番薯糖水) is my favourite sweet soup: it is made with sweet potatoes, ginger, and raw cane ( – je, in Cantonese). I love the strong spicy flavour of ginger and the soft texture of the root.

* tòhng-séui 糖水 (lit .sugar-water) is both the name for simple syrup (sugar syrup) and sweet soup.
Sweet potato sweet soup

The potato or yam is in the same genus and a member of the water spinach family. There are many types of sweet potatoes; some have red skin, some yellow brown skin and their flesh vary from white to pale yellow to bright orange red. The yellow skin type is said to be tastier than the purple one and thus better for making sweet soups.

(Back) red-heart sweet vegetable (紅心甜菜 – hùhng sâm tìhm-choi)
(Front left) orange-red heart sweet vegetable
(橙紅心甜菜 – chàahng hùhng sâm tìhm-choi)
The yellow skin potatoes (left) are labelled as gâi-daahn choi 雞蛋菜
(Lit. chicken egg vegetable) as the flesh is bright orange (egg yolk)

I found another type of sweet potato/yam at the wet market called “purple-heart-yam” 紫心薯” (jí-sâm-syùh). The skin of the heart-shape potato is dark brown and dotted with eyes and rough hair. The yam has a vivid purple colour flesh.

(The 2 lobes are joined and form a heart shape)

Raw purple-heart-yam cut into big chunks
On that day, next to the purple-heart-yam I also found yacon. I have never tried this root before. The latter’s tuber skin is thin, light brown and covered with an ochre-coloured soil. It’s crispy and juicy like an apple and tastes like jicama (yam bean - sâ-got 沙葛). It has a slight floury texture. Yacon can be stir-fried, braised with meat or cooked into sweet soups.

The lady I bought the purple-heart yam and yacon from asked me if I had ever tried to add some “tìhm-jáu-joù” and pointed to a glass jar in front of her. I asked: “What is it – Mat-yéh-léh-ga?” The label reads: “Wine Taste Rice” or loùh jòu in Cantonese (醪糟 lit. wine lees - distilled grain) but this is better known as Chinese rice pudding. The lady added that “tìhm-jáu-joù” (甜酒 lit. sweet-alcohol-distilled grain) was used to sweeten drinks and soups and add a subtle rice alcohol flavour.

Chinese rice pudding
Chinese rice pudding is made with glutinous rice, water, maltose, and yeast (rice wine yeast). This brand also has Chinese wolfberry (杞子- géi-jí). It has 0.2% alcohol content.

Yacon (left) and purple-heart-yam (right)


Sweet potato sweet soup

Recipe adapted from “Cook Like a Master Chef -Tips for kitchen novice” by Alvin Liu & Eric Lai.

  • 800g of sweet potato (peeled and cut into irregular shapes)*
  • 60g ginger, sliced**
  • 3 raw slab sugar (甘香蔗片糖 gâm-hêung-je-pin-tòhng)
  • Chinese rice pudding, to taste

  1. Bring to a boil 4 bowls of water - with ginger - into a large pot. Reduce heat and cook for 10 minutes.
  2. Add sweet potato. Bring to a boil. Reduce heat and simmer for 8 minutes.
  3. Add sugar slabs and cook over low heat till they have dissolved. Turn off heat.
  4. Add (optional) Chinese rice pudding. Stir well and serve.

* Irregular pointed shapes unleash the real flavour: Cut the potato into irregular shapes at an angle so that the whole piece of sweet potato receives equal amount of heat. This ensures its authentic taste comes through.
** Crush the ginger with its skin on to release its flavour.

The pink tuber was overcooked!
(Its flesh is much softer than yacon’s)
Sweet potatoes are best during autumn and winter. If we don’t want to cook ourselves we can either have it in sweet soup at local restaurants (not all places have this item on their menu as this is rather cheap) or roasted (sold in the street by hawkers).

Hawker selling sweet potatoes
I also found a shop in Mongkok (Bute Street) which is selling sweet potatoes baked in a large cauldron. They are so yummy!

Baked sweet potatoes
Let's enjoy eating sweet potatos!

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