Step 1

Preheat the oven to 200C / 400F.

Step 2

First, we'll get the dal simmering. Add the red lentils, coconut milk, salt and water into a saucepan and bring to a gentle boil. Stir and allow to simmer over a very low heat. The lentils will soften and turn creamy after about 15-20 minutes, but you can just let them bubble away until the sweet potatoes are ready.

Step 3

Next, we'll get the sweet potatoes roasting. Scatter the cubed sweet potato and onion slices into a lightly oiled baking dish (ideally 9x13' with high sides). Drizzle with olive oil, add salt and pepper to taste and then place in the oven for 20 minutes.

Step 4

Meanwhile, measure out and prep your spices and aromatics. Using a pestle and mortar, lightly crush the cumin and fennel seeds. Add to small bowl with the garam masala, chili powder and smoked paprika. Chop your ginger, garlic and cilantro (coriander).

Step 5

After 20 minutes in the oven, check in on the sweet potato and onion. The sweet potato should be soft and brown at the edges, and the onions a little bit crispy and caramelised. Give them a little more oven time if needed.

Step 6

Remove from the oven and immediately pour the spices, ginger and garlic into the pan and mix through. Add the butter to the dish, then place back in the oven for another 2-3 minutes, or until the spices are fragrant and the butter is melted (it may even be bubbling a little). Be careful not to leave it in the oven any longer than this - you don't want it to dry out or for the spices to burn.

Step 7

Now pour the cooked lentils into the pan with the sweet potatoes and onion. Add the cilantro and a couple squeezes of lemon juice. Stir to combine, making sure the butter and spices infuse through all of the dal. You can use a wooden spoon to break up some of the sweet potato cubes if you wish, though it's fine to leave them all whole.

Step 8

Serve immediately, with rice and/or naan, and additional lemon slices for squeezing if desired.