Heat oil in a wide pan over medium heat. Add cumin seeds and allow them to sizzle and release their aroma.
Stir in the minced ginger and garlic. Sauté for 30 seconds until fragrant.
Add the chopped onions and cook, stirring occasionally, until they turn translucent.
Now add the drained potato cubes and green chili. Stir-fry for 2 to 3 minutes. Cover the pan and cook over low to medium heat until the potatoes are halfway cooked, stirring occasionally. If needed, sprinkle a little water to help them cook faster.
When the potatoes are slightly tender but not fully done, add the cauliflower florets. Stir-fry for 3 minutes to coat the florets in the aromatic base.
Add the red chili powder, turmeric, roasted cumin powder, garam masala, and coriander powder. Mix well to distribute the spices evenly.
Sprinkle 2 to 3 tablespoons of water over the vegetables or around the edges of the pan to maintain moisture. Stir gently to combine.
Cover and cook the mixture, checking and stirring every few minutes, until both the potatoes and cauliflower are nearly fork-tender. Add salt and continue to cook on low heat, covered, until the potatoes are completely soft. The vegetables will release moisture, helping everything cook through—be careful not to overcook the cauliflower; it should remain slightly crisp yet fully cooked.
Add in the tomatoes and kasuri methi. Increase the heat to medium-high and cook, stirring often, until the raw tomato smell dissipates and the mixture thickens slightly. This should take about 2 to 4 minutes. Add a touch more oil at this stage if the mixture feels too dry.
If using, sprinkle amchur for a tangy lift. Finish with a handful of fresh coriander leaves and a squeeze of lemon juice if desired.
Serve hot with roti, naan, paratha, or steamed rice for a comforting, flavorful meal.