First, prepare the lentils. Soak for at least 2 hrs or overnight. Heat the oven to 180C/160C fan/gas 4. Mix the squash, garlic, shallots, bay, thyme, oil and a pinch of sea salt in a roasting tin, cover with foil and roast for 45 mins. Remove the foil and roast for 10 mins more, until the veg is tender and caramelised at the edges. Remove from the oven and turn the heat up to 200C/180C fan/ gas 6. Toss the pumpkin seeds with the cumin, oil and a pinch of salt, and roast until popped, about 5-6 mins.
Meanwhile, put the lentils in a pan with the bay, garlic and a pinch of salt. Cover with water, bring to the boil, then simmer for 20-25 mins. Drain and remove the bay and garlic. Toss with the oil and black pepper.
Combine the yogurt and tahini Add the harissa to taste, then mix with the lentils. Squeeze the roasted shallots and garlic out of their skins and stir through the lentils along with a drizzle of oil from the tin.
Serve the squash on the lentils, sprinkled with the coriander and seeds, and the yogurt on the side.