Peel and finely slice the onion. Finely mince the garlic and grate or finely mince the ginger. If using fresh tomatoes, core and roughly chop them; if using canned crushed tomatoes, have them measured and ready.

Toast and sweat aromatics

Heat a wide sauté pan over medium heat. Add vegetable oil and 2 tablespoons butter. When butter melts and foams, add sliced onion and a pinch of salt. Cook, stirring frequently, until the onions are soft and beginning to turn golden, 8–10 minutes. If the onions brown too fast, reduce heat slightly.

Add garlic, ginger and chilies

Add the minced garlic, grated ginger and chopped fresh hot red chilies to the pan. Sauté for 1–2 minutes until fragrant, taking care not to burn the garlic.

Build the tomato base

Stir in the tomato paste and cook for 1 minute to remove its raw edge. Add the chopped or crushed tomatoes, ground chili powder, ground coriander, ground cumin, turmeric and salt. Stir to combine.

Simmer

Bring to a gentle simmer, then reduce heat to low. Add the remaining 2 tablespoons butter and 1/2 cup water. Simmer uncovered, stirring occasionally, for 12–15 minutes until the sauce thickens and the flavors concentrate. Taste and adjust salt or chili heat as needed.

Topping / Served With

Season cottage cheese or yogurt

While the sauce simmers, prepare the spiced cottage cheese or yogurt. In a bowl, combine the crumbled cottage cheese or thick yogurt with chopped green chili (if using), chopped cilantro, lemon juice, black pepper and chaat masala (if using). Stir gently to combine and taste; adjust lemon, salt or chili to preference.

Combine to serve

When the sauce has finished simmering, spoon the hot buttered tomato-onion sauce into a shallow serving dish. Dollop or spread the spiced cottage cheese or yogurt on top or alongside the sauce as preferred — some like it fully mixed in, others prefer pockets of cool creaminess.

Finish and serve

Drizzle the teaspoon of ghee or melted butter over the top, sprinkle the toasted crushed cumin seeds and chopped cilantro. Add thinly sliced onion rings on the side if desired. Serve warm with flatbread or rice.

Garnish

Toast cumin: In a small dry skillet over medium heat, toast the cumin seeds until fragrant, about 30–60 seconds, then crush lightly between your fingers or with a mortar and pestle and sprinkle over the finished dish.