Rinse the chicken with salt and let it drain.

Make the broth: In a large pot, add 6 1/3 cups water (1.5 liters), a few slices of ginger (lightly charred), a peeled onion, and a pinch of salt. Bring to a boil, then add the chicken. Once it returns to a boil, lower the heat to prevent the chicken skin from splitting or the meat from getting mushy. Simmer for 30-40 minutes, then remove the chicken and let it cool.

Prepare a spice bag: Add 2 tablespoons pho spice mix, half an onion, and cilantro roots (if available) to a small cloth bag. Tie it closed and add it to the broth. Simmer for another 15-20 minutes, then remove the spice bag. You can also use star anise and cinnamon sticks instead of the spice mix if you prefer.

Season the broth with 2 tablespoons fish sauce, 2 tablespoons sugar, 1 tablespoon salt, and 1/2 tablespoon MSG (optional). Adjust the seasoning to taste. The broth is now ready.