Korean Sweet Potato Tart (Goguma Tart)

One of my favorite foods in the winter is Korean sweet potatoes (goguma 고구마). Sweet potatoes often found and used in Korean recipes are different from the ones we find most common here in the States. There are two main Korean varieties – mul goguma and bam goguma. Mul goguma is more pale yellow in the inside and bam goguma has more a of a golden pale yellowish flesh but both have purple brown skin.  Mul goguma is more often used for baking/roasting whereas bam goguma is for steaming but honestly, both work great and in many Korean grocery stores here the variety isn’t written so I won’t really know which one it is until I go home and I’m peeling a steamed one to stuff in my mouth! Even then, I can’t really tell. (My dad prefers mul gugomas).
 
For the most part, these are much sweeter than the sweet potatoes found in our normal American grocery store. And Koreans LOVE to use these gogumas in everything from soups, stews, side dishes and desserts! The flavors are also found as crackers and chips even, so, basically, really really popular.
And with goguma being in season during late fall/winter, today is goguma tart day! I scoured the internet for some fun tart recipes and was intrigued by this one here. It took a few trials and errors because Korean recipes really put a lot into the guessing game at times. I made this tart in different kitchens, for different occasions (Thanksgiving at the in-laws!!) and in different tart pans – 6 inch circle and 14×5 rectangle. Yums. After baking the tart in our small Boston kitchen, I hulled all of our baking supplies back down to the Northern Virginia area so I could do some holiday baking while we were in town. And, it was a hit! I wrestled with it a little bit and broke out a sweat thinking about taking it to the in-laws but alas, Thanksgiving was delicious all around!
korean sweet potato tart (goguma tart)
The tart begins with a buttery crust. You can use your favorite sweet tart crust, or of several I’ve used, joyofbaking’s tart has given me the most success with the least amount of shrinkage. I added a layer of chopped toasted walnuts on top of the crust to act as barrier between the crust and filling. It was initially driving me nuts that my buttery crust bottom was softening too much from the filling but the wall of walnuts helps!! (you can ask my husband who I made taste all of them like a lab scientist). Finally the tart is filled with a creamy sweet potato mousse and topped off with slightly caramelized sweet potato chunks, nuts and cranberries. The tart is not too sweet and perfectly satisfies the sweet tooth while not being too indulgent. Perfect with a cup of hot tea as a mid-day snack or to wind down after all the shopping going on!
korean sweet potato tart (goguma tart)
Print Recipe
Caramelized Korean Sweet Potato Tart (Goguma Tart)
Buttery crust tart filled with a luscious korean sweet potato mousse filling and topped with slightly caramelized sweet potato chunks, nuts and cranberries. Not too sweet but still perfectly satisfies the sweet tooth while not being too indulgent.
Servings
One 14x5 rectangle or 9 inch round tart pan
Ingredients
Sweet Pastry Crust
Goguma Mousse Filling
Goguma Topping
Servings
One 14x5 rectangle or 9 inch round tart pan
Ingredients
Sweet Pastry Crust
Goguma Mousse Filling
Goguma Topping
Instructions
Pastry Crust
  1. In a bowl, whisk the flour with the salt. Place the butter in a separate bowl and beat with a hand or stand mixer until softened. Add sugar into the butter and beat again until light and fluffy. Slowly add in a beaten egg until just incorporated. Add the flour mixture (step 1) into the butter bowl and mix until the dough forms a ball.
    korean sweet potato tart (goguma tart) - tart crust prep
  2. Slightly flatten the dough into a circular disc, cover with plastic wrap and refrigerate until firm (at least 30 minutes). Butter or oil a 14 x 5 inch rectangle or 9 inch round tart pan.
  3. Once the dough is chilled, roll it out to be about an inch bigger than the bottom of the tart pan. Evenly pat in the dough, starting from the bottom and up to the sides of the tart pan. Cut off any extras. Cover the tart pan with plastic wrap again and place in freezer for about 15 minutes. (This will help minimize the puffing rise that can occur on the bottom of the tart pan while it bakes. )
  4. Preheat oven to 400 degrees. Lightly prick the bottom of the tart with a fork to further prevent the dough from puffing up as it bakes. Bake for 5 minutes.
  5. Reduce oven temperature to 350 degrees F and continue to bake for about another 8-10 minutes or so until the crust is lightly golden but not completely baked. (To fully bake, it will be another 15 minutes but for this recipe, we will bake more later).
  6. Optional: Layer toasted walnuts over the crust. This acts as a wall between the crust and soft mousse so it doesn't get too soft at the bottom.
  7. Optional: Layer toasted walnuts over the crust. This acts as a wall between the crust and soft mousse so it doesn't get too soft at the bottom.
Goguma Mousse Filling
  1. Steam the gogumas in a steamer. Cook over water until soft. **I tested the microwave which is popular way to steam gogumas directly for consumption but I noticed that it didn't mash to be as creamy in the microwave as over the pot. If you don't have a steamer insert for a pot, you can directly place the gogumas directly in a pot of water. Also, the gogumas will lose a slight bit of weight as it steams so I aim for about 285-300 g of uncooked goguma
    korean sweet potato tart (goguma tart) prep
  2. Measure 250g of steamed goguma. Add in the rest of the mousse ingredients and mix well until all incorporated. Spoon in the mousse filling evenly over the walnut later in the crust.
Goguma Topping
  1. Cut the uncooked goguma into about 1 cm (2/5 inch) cubes. Sit the cubed uncooked goguma in water for about 10 minutes so some of the starch will soak out. Take the cubed goguma out of the water and dry on paper towels.
    korean sweet potato tart (goguma tart) prep
  2. Bring to a boil the heavy cream, sugar, honey and butter in a fry pan or small pot. Once the pot begins to simmer/boil, add in the cubed goguma.
  3. Once the liquid has reduced by about half, add in the nuts and cranberries. Reduce until the liquid has all evaporated and only the toppings are left with some syrup! Pour the topping evenly on top of the goguma mousse.
    korean sweet potato tart (goguma tart) prep
  4. Bake at 350 degrees F for about 12 minutes. Increase oven temperature to 400 degrees F and bake for another 10-15 minutes until the topping seems to look slightly browned. Keep check that the crust doesn't burn. If the crust seems to start browning too much, place some foil just on the sides of the crust.
  5. Optional: I like to cover the sides of the crust and broil for about 30sec - 1 minute. Keep a close eye on this because it will burn real fast! Don't ruin all your hard work at the end!
    korean sweet potato tart (goguma tart)
Recipe Notes

This recipe is adapted from a Korean recipe which is measured in grams so I highly recommend measuring by weight if possible. I've written out by cups/Tbsp to the best of my ability.

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