If not using pre-cooked potatoes, cook them in the microwave or boil them until tender.
Slice them finely with a knife and set aside.
Heat oil in a small non-stick frying pan or skillet over medium heat.
Add cumin seeds to the hot oil and fry for about half a minute until aromatic.
Add diced tomatoes and sliced potatoes to the pan.
Sprinkle salt, turmeric powder, and chili powder (if using) over the mixture.
Stir well to combine.
Cook for about 10 minutes, stirring occasionally, until the tomatoes are softened and the flavors meld together.
Pour in 1/2 cup of warm water.
Stir gently and simmer for a few minutes to allow the flavors to blend further.
Garnish with chopped cilantro/coriander leaves before serving.