Preheat the oven to 350°F.
Put the onion, squash, ginger root, garlic, turmeric, and curry powder into a large roasting pan. Drizzle over the olive oil and season with a teaspoon of sea salt and a generous amount of black pepper. Toss everything together so that it’s all nicely coated, then spread out in a single, even layer.
Place the pan in the oven and bake for 10 to 12 minutes, until the squash and onion have taken on a little color.
Remove the pan from the oven and add the lentils, tomatoes, coconut milk and stock. Stir well and return to the oven for 30 minutes, until the squash is just tender and the lentils are soft.
Season and squeeze over some fresh lemon juice to taste, then serve with a dollop of coconut yogurt.
Scatter with cilantro and chili flakes (if using), to serve.