Set out a medium sized mixing bowl. Slice the chicken breasts into thin strips and place them in the bowl. Add the oyster sauce, cornstarch, and 1/2 teaspoon of chicken base. Toss well to mix and coat all the chicken pieces in the marinade. Set aside.
Set out a small bowl. Add the rice to the bowl. Then fill it with cold water and stir the rice with your hand to wash. Drain off the water and rinse the rice again two or three more times to remove the extra rice starches. Set aside.
Set out a large 6 to 8-quart Instant Pot. Set the instant pot on SAUTE. Then add in the sesame oil, scallion whites, and grated ginger. Stir and sauté for 2 to 3 minutes to soften. Then add in the washed jasmine rice, the remaining 1 ½ teaspoons of chicken base, and 8 ½ cups of water. Stir well.
Lock the Instant Pot lid into place. Set the IP on PRESSURE COOK HIGH for 23 minutes. Once the beeper goes off, perform a NATURAL RELEASE. When the steam button valve drops, it is safe to open the Instant Pot.
Now set the Instant Pot back on the SAUTE setting. Stir in the chicken and marinade, stirring well to separate the chicken pieces. Simmer the chicken congee for 3 to 5 minutes to cook the chicken and thicken the porridge.
Once the chicken is fully cooked, ladle the congee into bowls. Garnish with the chopped scallion greens.
You can also make your chicken congee bowls fancier with fried onions, soft boiled eggs, crushed red pepper, and furikake.
Notes
Stovetop Instructions: Set a large 6 to 8-quart sauce pot over medium heat. Sauté the onions and ginger as directed. Then add in the rice, chicken base, and water and bring to a boil. Once boiling, stir well, then lower the heat to medium-low and simmer for about one hour. This rice should be very soft, and the porridge should be thick but still slightly soupy. Then stir in the chicken pieces and simmer another 3-5 minutes, until the chicken is cooked through.Let cool completely, then transfer to an airtight container. Chicken congee will keep well for up to 3-4 days in the refrigerator.