Prepare the Fish Paste (Dough):

• Start by cleaning the fish fillets. Remove any skin and bones, and then grind the fish using a food processor or mortar and pestle to create a smooth paste.
• In a mixing bowl, combine the ground fish paste with salt, pepper, minced garlic, sugar, fish sauce (if using), and the egg. Mix thoroughly until the mixture is smooth and slightly sticky.
• Gradually add in the tapioca flour, mixing it in a little at a time. You may need to adjust the flour amount slightly, depending on the moisture content of the fish paste. The dough should be firm but pliable. If it’s too sticky, add a little more tapioca flour.

2. Shape the Pempek:

• Once the dough is ready, divide it into portions. You can shape the pempek into round patties, oval shapes, or the traditional pempek kapal selam, where an egg is stuffed inside the dough.
  • For pempek kapal selam: Take a portion of dough and flatten it in your hands. Place a raw egg in the center and seal the dough around it, forming an oval shape. Make sure the egg is completely covered by the dough.
• If you’re making regular pempek, form the dough into round or oval cakes, depending on your preference.

3. Boil the Pempek:

• Bring a large pot of water to a boil. Add a pinch of salt to the water. Carefully drop the shaped pempek into the boiling water in batches, ensuring they don’t stick together.
• Boil the pempek for about 10-12 minutes, or until they float to the surface and become firm. Use a slotted spoon to remove them and set them aside on a tray to cool.

4. Fry the Pempek:

• Heat vegetable oil in a deep frying pan or wok over medium-high heat. Once the oil is hot (around 350°F or 175°C), fry the boiled pempek in batches until golden brown and crispy, about 3-4 minutes per batch. Remove the fried pempek from the oil and drain on paper towels to remove excess oil.

5. Prepare the Cuko (Vinegar Sauce):

• In a small saucepan, combine the palm sugar, vinegar, tamarind paste, minced garlic, and water. Bring to a boil over medium heat, stirring occasionally until the sugar dissolves and the sauce thickens slightly (about 5-7 minutes).
• Add salt and pepper to taste, and if desired, add sliced red chilies for a bit of heat. Remove the sauce from the heat and let it cool.

6. Serve:

• Serve the fried pempek hot, with a generous drizzle of cuko sauce over them. Garnish with sliced cucumber and fried shallots if desired. Pempek is typically enjoyed as a snack, but it can also be served as a light meal.