Start by peeling the purple sweet potatoes and cutting them into thin slices for quicker cooking. Place them in a steamer and steam over medium-high heat for about 20 minutes, or until they are soft and easily pierced with a fork.

Once the sweet potatoes are cooked, transfer them to a blender or food processor. Add 200g of water (equal to the weight of the sweet potatoes) and blend until smooth to create a vibrant purple sweet potato purée.

Place the purple sweet potato purée in a large mixing bowl.

To the purée, add 80g white sugar, 4g high-sugar-tolerant yeast, and 300g all-purpose flour. Stir the mixture with a spatula or whisk until it forms a thick, slightly sticky batter. Make sure everything is well combined.

Cover the bowl with plastic wrap or a clean towel and allow the batter to rise in a warm place for about 45 minutes, or until it doubles in size. The batter will be filled with small air bubbles, indicating the yeast is working well.

After the batter has risen, use a spatula to gently stir it and release the trapped air. This process ensures the final cake has an even texture.

Next, add 15g corn oil and stir until the oil is fully incorporated into the batter. This will give the cake a lovely, moist texture.

Line your steaming mold (a round or square cake pan works well) with parchment paper to prevent sticking. Pour the prepared batter into the mold, spreading it out evenly. Gently tap the mold a few times on the countertop to remove any large air bubbles. If using, sprinkle your dried fruits (such as raisins or red dates) evenly over the top.

Cover the mold with a lid or plastic wrap, and let the batter rest for another 30 minutes to allow it to rise again. It should once again double in size.

Bring water to a boil in your steamer. Place the mold into the steamer and cover the lid. Steam the cake over medium-high heat for 30 minutes. Be sure not to open the steamer during this time, as the steam is essential for creating the fluffy texture.

After steaming, turn off the heat and allow the cake to sit inside the steamer for an additional 3 minutes. This resting time helps prevent the cake from collapsing when exposed to cooler air. Once done, remove the cake from the steamer and let it cool slightly before unmolding.

Slice the cake into pieces and enjoy it warm or at room temperature. The Purple Sweet Potato Fa Gao should have a soft, springy texture with a mild sweetness. The vibrant purple color and optional dried fruit topping make it an eye-catching treat.