How to Make Vietnamese Potato Jam
The key to making potato jam chewy, stretchy, and visually appealing is careful preparation and controlling the heat while cooking. Additionally, there are two extra steps after cooking to ensure the jam dries properly, doesn’t get sticky or watery, and is evenly coated with sugar.
Ingredients
- 500g potatoes
- 250g white sugar
- 1 tablespoon quicklime (edible lime)
- 1 tablespoon alum
- 1 vanilla pod
- Salt
Ingredient Notes
Quicklime (lime powder) can be found at local markets or stores that sell traditional offerings like betel and areca nuts. Alum is commonly sold at dried goods and spice stores. Lime helps firm up the potatoes so they don’t fall apart during cooking, while alum gives the jam its chewy texture. Both also have antibacterial properties, extending the shelf life of the jam.
To avoid burning the jam, use a thick-bottomed pan.
Instructions
Preparing the ingredients
Add 1 tablespoon of quicklime to a large bowl or basin, then fill with water and stir well. Use about 3-4 liters of water. Let the lime settle at the bottom, and use only the clear lime water, discarding the residue.
Peel the potatoes, rinse them, and slice them into round slices about half a centimeter thick, or cut them into pieces about 5-6cm long, as desired. Avoid cutting the potatoes too thick, as the moisture inside won’t evaporate properly during cooking, causing the jam to remain wet and sticky.
After slicing, soak the potatoes in a bowl of water with 1 tablespoon of salt to remove any sap. Stir well and soak for 5 minutes, then rinse thoroughly.
Place the potatoes in a basin and pour the lime water over them to soak. Soak for about 2-3 hours, or up to 4-5 hours if you have time.
After soaking, drain the potatoes and rinse them several times to remove the lime flavor.
Boil a pot of water, adding 1 tablespoon of alum, and stir. Make sure the water is enough to cover the potatoes. Once the water is boiling, blanch the potatoes for 2 minutes. Be careful not to overcook them, as they will become too soft.
After blanching, drain and rinse the potatoes several times with cold water to remove any alum residue.
Coating with sugar
Once the potatoes have drained (you can also use a fan to dry them or pat them with a towel), place them in a large bowl to coat with sugar.
The ratio of potatoes to sugar should be 1:1/2. Even if you prefer less sweetness, ensure that the amount of sugar is at least half the weight of the potatoes. Using too little sugar will prevent it from crystallizing and forming a white coating, leaving the jam sticky and moist instead.
You can add more sugar if you want a thick sugar coating. Cookbeo will share a tip in the next step.
Mix well to allow the sugar to dissolve into the potatoes. Let it sit for about 3-4 hours, stirring occasionally to speed up the sugar dissolving.
Cooking the potato jam
To cook the jam, you can either pour the entire sugar-soaked potato mixture into a pan or strain out the syrup, cook it until reduced by half, and then add the potatoes to simmer.
Whichever method you choose, it's important to start with medium heat (for example, on an induction stove with 8 levels, set it at 3). At this stage, there will be plenty of syrup, so you don't need to stir the potatoes frequently. Let the potatoes absorb the syrup and begin to dry. Stirring too often can cause the sugar to reabsorb unevenly.
When the syrup starts to thicken, bubbles will form and the syrup will become sticky. Lower the heat slightly, and add 1/2 to 1 vanilla pod. Stir gently until the sugar crystallizes and the jam feels heavy to stir. Lower the heat again and continue stirring until the jam dries and separates. The sugar should form a light white coating on the potatoes.
If you are cooking a large batch, it’s better to divide it into smaller portions to ensure the sugar coats evenly.
Another useful tip: If you don’t want too much sugar coating, wear gloves and gently press the jam to shake off excess sugar before turning off the heat. This also helps ensure the sugar coating is evenly distributed.
If the potatoes were cut too thick and remain moist inside after cooking, you can cut them into smaller pieces to let the moisture evaporate. Additionally, simmer on low heat a little longer to dry them out completely.
To further dry the jam and prevent moisture, you can sun-dry the jam for 2-3 hours, or place it in the oven at 100°C for about 30 minutes. If using the oven, keep the door slightly open to allow moisture to escape.
If you don’t have an oven, let the jam rest for 3-4 hours. Then, put it back in the pan and cook on low heat for 15-20 minutes until completely dry.
Once the potato jam has cooled, store it in a clean, dry jar with a tight lid and keep it in a cool place.
The potato jam is rich and nutty, with a soft, chewy center and a light sugar coating. The tip of shaking off excess sugar before turning off the heat makes it less sweet, resulting in a balanced and healthy treat.
Alternative Method
The recipe above uses lime and alum. However, if you cannot find these two ingredients, you can confidently make potato jam without them.
The method for making potato jam without lime is similar to what Cookbeo shared. Instead of soaking the potatoes in lime water, soak them in thick rice water or a mixture of rice flour and water. To replace alum during blanching, squeeze the juice of 1-2 lemons (depending on the amount of potatoes). The remaining steps are the same as the version with lime and alum.
Good luck!
