Heat cooking oil in a saucepan and fry chopped garlic and chopped ginger for a few seconds. Then add chopped onion and green chilies. Saute until the onions turn soft and pink.
Now add chicken pieces along with black pepper powder, turmeric powder, garam masala powder, and salt. Fry all the spices along with chicken on medium-high heat for a minute.
Add barley and little more than 4 cups of water. Place the lid and slow cook the soup for at least 30 minutes.
Once the chicken pieces are fully cooked, remove them from the soup.
Separate the meat from the bones and return the shredded chicken back to the soup. Discard the bones.
Finally, add quick-cooking oats, chopped mint leaves, and lemon juice. Place the lid and cook for another 5 minutes. Taste and adjust the seasoning and add butter.
Serve hot with bread.