Heat 2 tablespoons oil in a large saucepan or medium Dutch oven over medium heat.
Add chopped carrots and 2 tablespoons ginger; cook, stirring often, until the carrots begin to soften, 5 to 7 minutes.
Stir in 1½ teaspoons coriander, 1 teaspoon cumin and ½ teaspoon salt; cook, stirring constantly, until fragrant, about 1 minute.
Add trimmed chicken breasts, 6 cups broth and the diced potatoes; bring to a vigorous simmer over high heat.
Reduce heat to maintain a gentle simmer; cover and cook until the potatoes are tender and an instant-read thermometer inserted into the thickest part of the chicken registers 165°F, about 10 minutes.
Transfer the chicken to a plate and let cool slightly, about 5 minutes.
Meanwhile, add 1 package frozen spinach to the soup; simmer, stirring occasionally, until heated through, about 2 minutes.
Stir in 1½ teaspoons tamari.
Thinly slice the chicken against the grain and return it to the soup.
Variations
You could substitute white potato for sweet potato.
You could add cubes of butternut pumpkin
You could add zucchini near the very end
