The magic of Bantan soup lies in the flour lumps. Traditionally, they are made by rubbing flour with water and a small amount of broth in one's hands until small, irregular pieces of dough, similar in size to grains of rice, are formed.
The base is a simple, long-simmered broth from meat and onion, ensuring the soup is extremely nourishing yet light.
In a large pot, heat a little oil (if using lean meat). Add the diced meat and brown it.
Add the onion, garlic (if using), and 1.5 liters of water.
Bring to a boil, reduce the heat, and simmer covered until the meat is tender (about 30 minutes). Skim any foam from the broth.
Place the flour and salt (for the lumps) in a bowl. Make a well in the center.
Pour cold water or 2-3 ladles of hot meat broth into the well (or both).
Use your hands (ideally your palms) to start mixing the liquid with the flour. Rub and grind the flour with the liquid between your fingers to create small, irregular, mushy lumps that are neither dough nor loose flour. The goal is lumps the size of rice grains, some may be larger.
Bring the broth in the pot back to a gentle boil. Add salt and pepper.
Gradually sprinkle the prepared flour lumps into the boiling broth, stirring continuously to prevent the lumps from sticking together into one large ball.
Simmer for another 5-7 minutes until the lumps are cooked and the soup thickens to the desired porridge-like consistency.
Remove from heat.
Serve the Bantan soup hot, garnished with chopped scallions, which add a fresh taste and color.