Heat oil in a wide pan over medium heat and add cumin seeds. Once they splutter, add chopped onion and cook until translucent with light golden edges. This slow browning forms the backbone of flavour and prevents a flat-tasting curry later.

Add ginger, garlic, and green chillies to the pan. Stir continuously and cook until the raw smell fades. Keep the heat moderated to avoid scorching, as burnt aromatics can overpower the mild sweetness of coconut milk.

Add turmeric, coriander, and red chilli powder. Stir quickly so the spices coat the oil evenly. This short blooming step unlocks aroma without bitterness and ensures the spices dissolve smoothly into the sauce.

Add the chopped tomato and cook until soft and fully integrated into the spice base. The mixture should look cohesive, with oil just beginning to separate at the edges. This signals that the masala is properly cooked.

Add the cooked lentils along with their liquid and stir gently. Pour in coconut milk and bring the curry to a slow simmer. Avoid boiling aggressively, as high heat can cause coconut milk to split and lose its smooth texture.

Add salt and simmer briefly until the curry reaches a steady, spoon-coating consistency. Turn off the heat, stir in fresh coriander, and let the curry rest. This pause allows flavours to settle and the texture to stabilise.