In a wide pan over medium heat, add rice flour. Cook, stirring regularly, for about 3 to 5 minutes or until lightly golden. Remove from pan and set aside.
In a pot over medium heat, heat oil. Add onions and garlic and cook until softened.
Add chicken and cook, stirring regularly, until lightly browned.
Add fish sauce and cook for another 1 to 2 minutes.
In a bowl, combine water and annatto powder. Stir until well-dispersed and add to pan.
Bring to a boil, skimming scum that may float on top. Lower heat, cover, and simmer until chicken is tender.
Add eggplant and long beans and cook until tender yet crisp.
Add peanut butter and stir until well blended.
In a bowl, combine rice flour and one cup of broth from the pot. Stir until very smooth and without lumps.
Slowly add to the pot, whisking to prevent lumps. Season with salt and pepper to taste. Continue to simmer until sauce is slightly thickened.
Add pechay and cook for another 2 to 3 minutes or until tender yet crisp.
Serve hot with sauteed shrimp paste on the side.