In a large pot, heat the vegetable oil over medium heat. Add the chopped onion and sauté until translucent and slightly golden, about 5-7 minutes.
Stir in the minced garlic and grated ginger, cooking for an additional 1-2 minutes until fragrant.
Add the diced tomato to the pot, and cook for another 3-4 minutes until the tomatoes break down and form a sauce.
Sprinkle in the curry powder, turmeric, and ground cumin, stirring well to coat the onion mixture in the spices. Cook for 1 minute to toast the spices.
Add the cubed potatoes to the pot, mixing them into the spiced onion mixture.
Pour in the coconut milk, season with salt and pepper, and bring the mixture to a simmer.
Cover the pot, reduce the heat to low, and let the curry cook for about 20-25 minutes or until the potatoes are tender, stirring occasionally.
Once the potatoes are cooked through, squeeze in the lime juice and adjust seasoning if needed.
Remove from heat and garnish with fresh coriander leaves before serving.
Notes
Serve with fluffy basmati rice or warm naan bread. Drizzle extra lime juice before serving for added flavor.