Heat the olive oil in a large skillet over medium-high heat. Cook and stir the onions in the hot oil until translucent, about 5 minutes. Add the ginger-garlic paste and continue cooking another 5 minutes. Reduce heat to medium; stir the tomatoes into the mixture and cook until the tomatoes are pulpy, 5 to 10 minutes. Season with the cayenne pepper, curry powder, garam masala, turmeric, and cumin; cook and stir another 5 minutes.
Add the chicken and potatoes to the mixture in the skillet; simmer, stirring occasionally, until the potatoes are tender and the chicken is no longer pink in the center, about 20 minutes. Sprinkle the cilantro over the mixture and continue simmering another 10 minutes. Serve hot.
