Preheat your oven to 180°C.Toss the diced sweet potato and red pepper with 15ml of oil and a pinch of salt. Spread them on a lined baking tray. Place the whole tomatoes on the same tray.Roast for 20–25 minutes, until the vegetables are tender and lightly caramelized. Once done, remove the skin from the tomatoes and mash them with a fork.
In a medium-sized pot, combine the red lentils, vegetable stock, and cinnamon stick. Bring to a boil, then reduce to a simmer and cook for 30 minutes, stirring occasionally.
Heat 15ml of vegetable oil or ghee in a frying pan over medium heat. Add the diced onion and sauté for 5 minutes, until translucent.Stir in the garlic, turmeric, cumin, garam masala, and chili powder. Cook for 1–2 minutes until fragrant. Add a little more oil if the mixture is too dry.Transfer this spice mixture into the pot with the cooked lentils.
Add the coconut milk to the lentils and bring everything back to a gentle simmer. Stir in the roasted vegetables and mashed tomatoes. Mix well. Add the spinach, lime juice, and adjust the seasoning with salt and chili powder to taste.Simmer for a few more minutes until the spinach is wilted and the dhal reaches your desired consistency. Add a splash of water if it’s too thick.
Garnish with fresh coriander if desired. Serve with rice, naan bread, or enjoy it as a hearty bowl on its own.