In a large Dutch oven over medium-high, heat the oil until barely smoking. Add the chicken skin side down and cook without moving until well browned, 5 to 7 minutes. Flip and cook until lightly browned on the second sides, about 5 minutes. Transfer the chicken skin up to a plate; remove and discard the skin. Pour off and discard all but 2 tablespoons fat from the pot.
To the pot over medium, add the onion, cilantro stems and jalapeño; cook, stirring, until the onion is lightly browned, about 5 minutes. Add the curry powder, ginger and garlic; cook, stirring, until fragrant, about 30 seconds. Add the tomatoes, increase to medium-high and cook, stirring, until the moisture from the tomatoes evaporates, about 1 minute. Add the broth and ½ teaspoon each salt and pepper, then return the chicken and any accumulated juices to the pot. Bring to a simmer, then cover, reduce to low and cook, stirring occasionally, for 20 minutes.
Stir in the potatoes, return to a simmer and cook, uncovered and stirring occasionally, until a skewer inserted into the chicken and potatoes meets no resistance, 20 to 25 minutes. Off heat, stir in the cilantro leaves. Taste and season with salt and pepper.
