Kumquat chiffon cake

Recently a few bloggers enthusiastically exploring kumquat makes me realize that this fruit is so much underprivileged in my home town (Hongkong, China). The trees are cultivated in many farms, some of them are just meant to be for Chinese New Year's home deco. After the festival ended, we usually throw the whole tree (yes, the fruit too) out, and even laugh at our mothers how frugal they are when they picking off the fruits to make preserves. Kumquat's whole rinds are editable as the white part isn't bitter like that of lemon or orange. So I sliced the whole fruit and created these caramelized kumquat, topped on kumquat-scented chiffon cake.

Since I feel the oil in kumquat's skin is fairy high, I only intent to lend its aura in the cake, the cake will be finalized by marmalade filling and garnished by caramelized kumquat. If you rather enjoy eating the cake on its own without filling or anything else, you may add kumquat zest into the cake batter.

Ingredients (yield a cake with 10-inch dia.)

• To caramelize kumquat: 2/5 cup white sugar, 2/5 cup damerara sugar, 12 oz kumquat, 1/2 cup water
• For the cake (for 10-inch tube pan):
• 1 cup cake flour
• 1 tsp baking powder
• 1/2 cup kumquat syrup (left from caramelizing procedure), add orange juice if you don't get enough
• 6 yolks
• 1/3 cup corn/ veg oil
• a couple dashes of vanilla extract
• 7 egg whites
• 5 Tbps sugar
• 3/4 tsp cream of tartar
• a few pinches of salt
• for filling/garnish: marmalade and caramelized kumquat

Directions:

1. To caramelize kumquat: Wash and slice kumquat, about 1/4-cm thick, seed out. In a small pot, bring the water and sugars to boil, and simmer over medium - medium/low heat for 10 minutes. Add kumquat, continue to boil for another 15 minutes. Drain, and save the syrup.
2. To make the cake: Preheat the oven to 350F. Get the baking pan ready. In a large mixing bowl, combine flour and baking powder.
3. In a medium mixing bowl, beat the yolk with a pinch of salt until slightly pale, add oil and kumquat and beat until they corporate. Add two dashes of vanilla extract. Combine the yolk mixture and the flour mixture. Set aside.
4. In another big mixing bowl, add a pinch of salt into the egg whites, beat until frothy, add cream of tartar, beat until soft-peaked, add sugar, little by little, and beat until hard-peaked.
5. Use a big spatula, scoop 1/3 of the white egg foam into the flour/yolk mixture, gentle mix until combine. Then add another 1/3, fold, and the last 1/3, fold the batter very carefully. Pour the batter into the pan. Bake in the 350F oven for 5 minutes, then lower to 330F and bake until done, test with inserting toothpick into cake and it should come out (almost) clean. Total baking time is about 40 minutes.
6. With some supports, turn the pan upside-down to cool for 2 hours, unmold. Slice the cake horizontally, spread with marmalade, topped with caramelized kumquat as garnish

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