Preheat oven to 400°F (200°C). In a large bowl, toss butternut squash and onion with peanut oil.
Arrange squash and onion on a baking sheet. Season with salt and pepper.
Roast in oven until squash and onion are tender and lightly browned, 25 to 35 minutes. Remove from the oven and set aside to cool. NOTE: Onions may cook faster than the rest of the squash and may need to be removed earlier.
Now, let's make the lime tahini sauce. In a small bowl, whisk together tahini, lime juice, water, garlic and salt. Depending on the consistency of your tahini, you may need to add a little more water or tahini to reach the consistency of a thick sauce.
Dinner's ready! Place your roasted squash and onions in a large serving bowl and drizzle with tahini sauce. Sprinkle with roasted pepitas, za'atar and parsley.
Notes
Adapted from Yotam Ottolenghi's Roasted Butternut Squash recipe found in Jerusalem.