In a large pot, rinse rice till water runs clear, about 3 to 4 times, drain.
Add 10 cups (2.4 liters) water to the rice and set it on the stove to boil. When water comes to boil, remove lid, add chicken breasts. As soon as water comes back to a boil, add salt and pepper and reduce heat to simmer for about 30 minutes. If porridge gets too thick at any point, stir in ½ cup (120ml) water to dilute.
Remove chicken breasts from pot with tongs. Shred the chicken breasts and return shredded meat to the pot.
Add ginger and one to two teaspoons of sesame oil to the porridge. Turn off heat.
Serve immediately with a sprinkling of green onions, pepper, and soy sauce. Add a few drops of sesame oil if desired.