Deseed the chilies: Cut the tops and bottoms, then cut the chili horizontally and scrape off the seeds.
Soak the chilies: Add the chilies to a bowl of warm water. Add the lemongrass stalks. Add brown sugar and soak for 10 to 15 minutes. Drain the water and set aside.
Blend the ingredients: Chop the lemongrass stalks into smaller pieces with the dried red chilies and lemongrass stalks. Add the rest of the ingredients to a blender and blend for a few seconds until they form a smooth paste. If the ingredients are not mixing, add two tablespoons of cooking oil and blend again.