Add oil to a pot with deep sides and over medium-high heat. When oil shimmers, add onion, carrot, celery, and garlic, and cook until softened, about 5-7 min.
Add grated ginger, turmeric, curry powder, salt, and pepper. Stir and cook until fragrant, about a minute.
Add chicken and stir to coat.
Add broth, water, and rosemary. Bring the mixture to a boil and add barley. Stir to mix.
Reduce the heat and simmer, covered for 30 minutes.
Stir peas into the soup and return it to a simmer. Taste for salt, adding more if needed. Serve hot.
