Heat the oven to 200˚C (400˚F). Put the squash on a baking sheet, drizzle with 1 tbsp olive oil and season with salt and pepper. Roast for 20 minutes or until tender, shaking the tray a couple of times to keep it from sticking. Simmer the lentils for about 15 minutes or until al dente, then drain.
Whisk together the dressing ingredients. Put the arugula in a shallow serving bowl and arrange the lentils and squash on top. Pour the dressing over and top with sesame seeds and spring onions