There’s no denying it: this tart is purple. It’s not
lavender or rose, it’s purple. The color didn’t come from a little dropper
bottle or baggie of magic powder, it came from purple potatoes. To be specific,
Okinawan sweet potatoes.
After seeing the little Chinese grannies at HT Market buying
gai lan (good choice) and garlic chives (even better choice), I knew that they
couldn’t be wrong about the “Hawaiian sweet potatoes”, or imo (in Japanese). Those
ladies know what they are doing! Sometimes I work up the courage to ask them
how to cook something (“stir-fry with a little oyster sauce”). Sometimes I
just put the strange looking fruit/vegetable into my basket and go about my
business.
If you haven’t started buying the some of the stuff that the little
Chinese grannies pick up at your nearest product stand or ethnic market, you'd better get on
it. Okinawan sweet potatoes may be harder to find than regular sweet potatoes,
but are worth seeking out. The bright purple flesh isn’t all just for show either,
there’s some serious nutrition behind this root vegetable. The violet pigment seen
in Okinawan sweet potatoes (as well as berries, eggplant, flowers and anything else
purple found in nature) comes from anthocyanins, which are powerful
antioxidants that not only provide protection from free-radical damage and offer
protection against harmful UV rays, they also attract hungry animals and
pollinators. Scientists are studying anthocyanins to fully understand the
effects they have on our bodies.
Food science geek alert: the color of anthocyanins is
very pH sensitive. In acidic environments, they appear more red and in basic
environments they appear more blue. That’s why one usually adds apple cider
vinegar to red cabbage for a lovely rosy hue—blue food can be off-putting
sometimes. Try adding vinegar and baking soda to glasses of grape juice and you’ll
see what I’m talking about!
Suitable for roasting, mashing, frying, baking, soups and
more, (hmm…kinda like a sweet potato?) Okinawan sweet potatoes lend themselves
and their beautiful purple hue to countless preparations. Like dessert. Like a sweet potato tart with a smooth filling and crumbly chocolate shortbread crust made with coconut oil. If you
haven’t sensed a vegetables-in-dessert theme on this blog yet, then keep
reading.
Nutrition Focus: Okinawan
Sweet Potatoes
- Good source of dietary fiber, shown to help with satiety, reduce blood cholesterol and control blood sugar levels.
- Low on the glycemic index, meaning glucose (blood sugar) will be released more slowly and steadily than foods high on the glycemic index. This is beneficial to everyone, but especially for diabetics and others whole need to watch their blood glucose.
- High in anthocyanins (antioxidants), which may help protect against cancer.
- Vitamin A to support cellular function and boost immune system.
- Vitamin C to protect cells from free-radical damage and improve iron absorption.
Okinawan Purple
Sweet Potato Tart
The crust is inspired by Dorie Greenspan’s chocolate
shortbread tart dough in Baking: From My Home To Yours, which is a true
pleasure to drool over. My favorite brand of coconut milk is Chaokoh, which can
be found at your nearest Asian supermarket or online.
Serves 10
Ingredients:
For the dough:
¾ cup (90 grams) whole wheat pastry flour½ cup (65 grams) all purpose flour
¼ cup (25 grams) cocoa powder
¼ cup (30 grams) powdered sugar
¼ teaspoon (1.5 grams) salt
9 tablespoons (130 grams) coconut oil, frozen and cut into small pieces
1 large (17 grams) egg yolk
For the filling:
4 medium (850 grams) Okinawan sweet potatoes3 large (150 grams) whole eggs
3/4 cup (150 grams) granulated sugar
¼ teaspoon (1.5 grams) salt
1 teaspoon (4 grams) vanilla extract
½ cup (120 grams) coconut milk
Optional, for
serving:
powdered sugarsliced mango, berries, kiwi, papaya or other seasonal fruit
Make tart dough. Pulse
together the dry ingredients for the dough until combined. Scatter the coconut
oil over the dry ingredients and process in 1-second pulses until the oil is in
bits the size of peas. Break open the yolk in a dish and pour about half of it
over the dry ingredients, then pulse a few times to combine. Add the remaining
yolk and continue to pulse until the dough forms large clumps.
Bake the tart
dough. Gently pat the dough into a 9-inch fluted tart pan. Freeze the tart shell
for 30 minutes or wrap 3 times in plastic wrap and freeze for up to 2 months. Center
a rack in the oven and preheat to 375°
F. Prick the dough with a fork, cover with foil and bake for 25 minutes. Reduce
the heat to 350° F
and leave the oven on. Remove the foil and transfer the crust to a rack to cool.
Make the filling. Peel
the sweet potatoes and cut into chunks. Place in a steam basket over boiling
water and cook until tender, about 12 minutes. While the potatoes are hot, pass
through a ricer or a food mill into a large bowl. Add remaining filling
ingredients and whisk together until smooth, then pour into the par-baked tart
shell.
Finish the tart. Bake
the tart for 45 minutes, until the filling is set and a toothpick inserted in
the center comes out clean. Remove the tart to a rack to cool completely. To
serve, cut into wedges and garnish with a dusting of powdered sugar and fresh
fruit.
that looks pretty yummy, i mean pretty and yummy! thanks for sharing. I'm glad the recipe will be on hand later...it's too hot to bake today!
ReplyDeleteThis looks incredible! You're so creative Emily!
ReplyDeleteThis looks incredible! You're so creative Emily!
ReplyDeleteThanks guys!
ReplyDelete