Start by soaking the dried red chilies in hot water for about 10 minutes until softened. Drain and place them in a blender along with the shallots and belacan. Blend until you achieve a smooth paste.
In a wok or large skillet, heat the 3 tablespoons of oil over medium heat until shimmering.
Add the blended spice paste to the hot oil. Sauté for about 5-7 minutes until fragrant and the oil starts to separate from the paste.
Pour in the tamarind pulp mixture and 3/4 cup of water. Stir well to combine, and allow it to simmer for about 5 minutes.
Add the prawns to the simmering sauce. Cook for 5-7 minutes, or until the prawns turn pink and opaque.
Stir in the kaffir lime leaves, salt, and sugar. Taste and adjust the seasoning as needed, then remove from heat.
Serve the Sambal Udang hot, garnished with additional lime leaves if desired. Pair it with steamed rice for a satisfying meal.
