Peel the potatoes and cut them into 1.5 cm (0.6 inch) cubes. Rinse and roughly chop the spinach. Mince the garlic and ginger finely.
Heat the oil in a large skillet over medium heat. Add the cumin seeds and cook until they crackle and become fragrant, about 30 seconds.
Add the ground turmeric, coriander, and chili powder to the skillet. Stir briefly and cook for 15 seconds until the spices release their aroma.
Stir in the minced garlic and ginger, cooking until fragrant and slightly golden, about 1 minute. The mixture should smell warm and inviting.
Add the cubed potatoes to the skillet. Stir well to coat them in the aromatic spice mixture, then cook on medium heat, stirring occasionally, until they develop a light golden crust, about 8-10 minutes.
Chop the tomatoes and add them to the skillet. Cook for about 5 minutes, mashing slightly to break them down, until the mixture thickens and the aroma turns tangy and spicy.
Toss in the chopped spinach and stir until wilted and bright green, about 2 minutes. If using frozen spinach, ensure it is squeezed dry before adding.
Season with salt to taste. If the curry is too thick, add a splash of hot water or broth and simmer for another 2 minutes to let flavors meld.
Turn off the heat and let the curry rest for 2 minutes. This helps the flavors deepen and meld together beautifully.
Spoon the warm, fragrant spinach potato curry into bowls, garnishing with fresh herbs if desired. Serve with rice or flatbread and enjoy the comforting, earthy flavors.