Peel and dice the potatoes into 1-inch chunks, ensuring they’re uniform for even cooking.
Heat the cooking oil in a large heavy-bottomed pan over medium heat until shimmering. Add the cumin seeds and toast until fragrant and slightly darker, about 30 seconds, listening for a crackle.
Add the chopped onion to the pan and sauté until golden and translucent, about 5-7 minutes, stirring frequently to prevent sticking or burning.
Stir in the minced garlic and grated ginger, cooking for about 1 minute until fragrant—watch for a bubbly, aromatic scent that signals readiness.
Mix in the ground turmeric and coriander, cooking for 30 seconds while stirring to toast the spices and deepen their aroma.
Add the diced potatoes to the pan, stirring well to coat them with the spices. Cook uncovered for about 5 minutes until they start to turn golden around the edges, making a gentle sizzling sound.
Pour in the canned diced tomatoes, stirring to combine. Bring the mixture to a simmer, then cover loosely with a lid and cook for 10 minutes, stirring occasionally, until the potatoes are tender and the sauce thickens slightly.
Stir in the frozen peas and cook uncovered for another 3-5 minutes until they are bright green and heated through, tasting and adjusting salt if needed.
Check the consistency—if too thick, stir in a splash of water and simmer briefly; if too runny, uncover and simmer until it reaches a velvety, coated texture.
Remove the pan from heat and let the curry sit for a couple of minutes to allow flavors to meld. Serve hot, garnished with fresh herbs if desired, alongside rice or bread.
