Prepare bones: Place bones with meat in hot boiling water separately to soak and remove blood and impurities. Rinse the bones in warm water to clean off leftover blood.
Roast aromatics: Roast onions and ginger until aromatic and slightly charred.
Make broth base: In a large pot, add hot boiling water, roasted onions, roasted ginger, celery, and cleaned bones. Add brown sugar and chicken flavor powder to enhance flavor.
Season broth: Add salt and optional MSG to the broth. Add star anise for aroma if desired, but use sparingly to avoid overpowering the broth.
Simmer broth: Bring broth to a boil, then reduce heat and let simmer for 1 to 2 hours or longer (overnight preferred) to extract flavors from bones and herbs.
Skim fat: During cooking, skim off any white fat or impurities that rise to the surface to keep the broth clear and clean tasting.
Final preparation: After simmering, remove bones and herbs. The broth is now ready to be used as the base for Lao pho or other soups.