These prawn and sweet potato fritters (aka Bánh Tôm Cổ Ngư or Bánh Tôm Hồ Tây) are quintessential street food of northern Vietnam. They’re fried to golden perfection and pairs perfectly with fresh herbs and dipping sauce.
One of the best things about living with my mom is learning to cook all of my favorite childhood food from her. One dish that she makes often is prawn and sweet potato fritter (aka Bánh Tôm Cổ Ngư or Bánh Tôm Hồ Tây), a quintessential street food of northern Vietnam. These fritters originated from a street called Cổ Ngư which ended at the well known lake called Ho Tay in Hanoi. My dad grew up on this street so he’s quite fond of these fritters. These prawn and sweet potato fritters are fried to golden perfection and pairs perfectly with fresh herbs and dipping sauce.
Tips for making the fritters perfect every time
To make these delicious fritters, you need a good batter, sweet potatoes, and head-on prawns. Get these three things right, and you’ll make the perfect fritters everytime. For the batter, it’s a simple mixture of rice flour, cornstarch, salt, and a touch of ground turmeric to add some color. I like the batter consistency just thick enough to hold the sweet potatoes and prawn together when they’re fried but not so thick that you feel like biting into a fried dough ball. Look for a consistency similar to a pancake batter. Test fry one to see how you like the taste and texture, and then adjust the batter as needed.
For the sweet potatoes, I like to cut them into batons about ¼ of an inch thick. When you cut them thin like matchsticks, you’ll lose out on the sweetness of the sweet potato. If you cut them too thick, they won’t be crispy when fried. I divide the sweet potatoes into 1 ounce portions to keep the size consistent for frying.
In Vietnam, these prawn and sweet potato fritters are usually made with small prawns but I find that the meat shrinks significantly after frying. With a large prawn, you can sink your teeth into these fritters and still taste the meat. The head and shell become crispy and delicious after frying so I prefer to leave them on. You can remove the head and shell before frying if you prefer.
Tips for frying the fritters
I found that the best temperature to fry these prawn and sweet potato fritters run between 340-350 degrees F. Make sure you don’t overcrowd the pan when frying or these fritters will turn out a bit soggy. I only have 2 to 3 fritters in the pan at a time with a thermometer attached to the side of the pan to keep the temperature consistent. Each fritter only needs about 3-4 minutes on each side. To keep them crispy and warm while you’re finishing up the batch, keep the fried fritters in the oven at 275 degrees F.
What to serve with the fritters
These prawn and sweet potato fritters taste great with a selection of Vietnamese herbs and dipping sauce. I used a combination of butter lettuce, mint, Vietnamese coriander (rau răm), perilla (Tía Tô), and Thai basil (Húng quế). Simply wrap the fritter in a lettuce along with the other herbs and dip everything in the fish sauce. Fried to golden perfection, these delicious fritters make the perfect meal!
Vietnamese prawn and sweet potato fritters
- 1 lb sweet potato, cut into batons (3-4 inches long and 1/4 inch thick)
- 1 lb prawns, head and shell intact
- 1 1/4 cups rice flour
- 2 tbsps corn starch
- 1/4 tsp turmeric
- 1 cup cold water (or sparkling water)
- 1 tsp salt
- 1/4 tsp freshly ground pepper
- butter lettuce
- Vietnamese coriander, shiso, Thai basil, mint for serving
- nuoc cham (dipping sauce) for serving
- 2 quarts vegetable oil for frying
- 2 garlic cloves, finely chopped
- 1 bird's eye chili, thinl sliced
- 1 tbsp fresh lime juice
- 3 tbsps granulated sugar
- 2 tbsps fish sauce
- 1/4 cup water
- Peel the sweet potatoes and cut them into batons, 3-4 inches long and 1/4 inch thick. Add the cut potatoes into a large bowl filled with iced water and let it stay in the fridge for 1 hour to crisp up. Drain well when ready to use.
- Whisk together the flour, cornstarch, turmeric and 1/2 tsp salt. Make a well in the centre. Gradually add enough water, whisking constantly, to form a smooth and thick batter. Let the batter rest for 30 minutes.
- Preheat the oven to 275 degrees F.
- Place the prawns in a bowl and season with remaining salt and pepper. Stir and allow to stand.
- Divide the potatoes into 1 ounce portions. You can also divide them based on how big you want the fritter to be but less than the size of your palm is best for frying.
- Heat the oil in a large saucepan over medium-high heat until it reaches 350 degrees F on a kitchen thermometer.
- Add the sweet potatoes and prawn to the batter and toss well to coat. Spoon each portion of the fritter into the heated oil and cook for 3-4 minutes on each side, until golden and crispy.
- Use a slotted spoon to remove them and drain on a plate lined with a paper towel. Repeat with the remaining portions until you’re finished frying.
- Transfer the fried fritters to the oven to keep warm.
- To make the dipping sauce, combine everything in a bowl and whisk together until combined.
- When ready to serve, place the herbs and fritters on a large serving platter. Wrap the fritter and a few herbs in the lettuce and dip it into the dipping sauce.