Turn Instant Pot to Saute(more) mode and heat half of the oil. Add garlic, green chilies, half of the ginger and cilantro stems. Mix well.
Add chicken breasts, black peppercorn, salt, water and broth. Give a quick stir and close Instant Pot with pressure valve to sealing.
Pressure cook for 10 minutes followed by Natural Pressure Release.
Open Instant Pot and take the chicken breasts out. Shred the chicken with a fork and keep aside.
Take a large bowl and strain the broth. Squeeze out any juices by gently pressing the stems in the strainer. Discard the stems from the strainer. Reserve the broth.
Rinse and dry the Instant Pot insert. Put the insert back and set the Instant Pot to sauté mode. Add the remaining oil, cabbage, carrots, and remaining ginger. Mix well.
Add shredded chicken, reserved broth, and corn starch water.
Mix well and bring the soup to a gentle boil. Turn Instant Pot off. Add fresh ground pepper, lemon juice, and chopped cilantro. Enjoy hot!