Soak the cauliflower florets in hot water with a pinch of salt for 2–3 minutes to remove any impurities. Drain and set aside. Skip this step if your florets are clean and pre-washed.
Heat mustard oil in a large, heavy-bottomed pan or kadhai until it begins to smoke lightly (this reduces its pungency). Reduce the heat to medium.
Add cumin, nigella, mustard seeds, dried red chillies and asafoetida. Let them sizzle until aromatic, about 30 seconds.
Add finely chopped onions. Cook until golden brown, stirring occasionally, about 5 – 6 minutes.
Add the grated/pureed tomatoes, turmeric powder, coriander powder, red chilli powder, and salt.
Cook the masala until the tomatoes break down and the oil separates from the masala, about 5 – 6 minutes.
Add the cubed potatoes, green peas, and cauliflower to the masala. Stir to combine nicely.
Add ¼ cup of water. Cover the pan with a lid and reduce the heat to low.
Allow the vegetables to cook, stirring occasionally to prevent sticking or burning. This should take about 15–20 minutes, depending on vegetables.
Once the potatoes and cauliflower are cooked, add fresh methi leaves, sliced ginger and green chilli. Sprinkle garam masala and amchur powder. Mix gently. Cook for 5 minutes over low heat without cover.
Garnish with freshly chopped coriander leaves before serving.
Serve aloo gobi warm with chapati/roti/paratha.