Combine chicken thighs, curry powder and 1 tablespoon ginger in a medium bowl; rub the seasonings into the chicken. Let stand at room temperature for 10 minutes.

Meanwhile, heat oil in a large Dutch oven or large pot over medium-high heat. Add cabbage and carrots; cook, stirring often, until softened, about 5 minutes.

Stir in the remaining 1 tablespoon ginger; cook, stirring constantly, until fragrant, about 1 minute.

Add broth, potatoes, salt and the seasoned chicken; bring to a boil over medium-high heat. Reduce heat to medium to maintain a simmer; cover and cook, undisturbed, until the potatoes are tender and the chicken shreds easily with a fork, about 15 minutes.

Remove the chicken to a cutting board and, using 2 forks, shred it into bite-size pieces; return to the soup.

Stir in peas and lemon juice. Garnish with cilantro, if desired.