Cut the lemongrass stalks in half. Discard the upper green halves. Take the lower halves chop off the end, and peel away a few of the tough outer layers. Dice the stalk into 1 inch pieces.
Dice the onion, garlic and ginger. Use a food processor, if needed. Heat coconut oil in a medium-sized stockpot over medium heat. Add the lemongrass, onion, garlic, and ginger and saute until fragrant and softened, about 5 minutes.
Add turmeric and chili powder. Mix well and saute another minute or two.
Add fish broth and bring to a boil. Reduce heat and bring to a simmer.
Add chickpea flour and stir until mixed well. Simmer for 10 to 15 more minutes until slightly thickened.
Add the fish. Simmer for about 5 minutes or until it's cooked through.
Prepare noodles according to package directions.
Add rice noodles to individual bowls. Ladle soup over the noodles. Add seasonings, to taste.
