Preheat the oven to 400F(200C). Toss the cauliflower, cauliflower leaves and butternut squash with the olive oil, curry powder, cumin seeds and some salt. Spread out in a large roasting tray and roast for 30-40 minutes, turning halfway through cooking, until tender and lightly charred.

Meanwhile, heat the olive oil in a large pan over low heat and add the onion and cook gently, stirring regularly, for about five minutes until softened. Add the garlic, chili, ginger, cumin, and garam masala and cook for a couple more minutes, then stir in the tomatoes, lentils, and stock. Bring up to a gentle simmer and leave to cook, occasionally stirring, for about 20-30 minutes until the lentils are soft and falling apart. Season generously with salt and stir in the lemon juice.

Serve the dhal and vegetables with rice and pita bread.