Preheat oven to 425° F. Toss diced squash, potatoes, and herbs in a tablespoon or two of avocado oil. Spread onto a baking sheet and roast for 20-25 minutes, until beginning to brown. In the meantime, toss the onion with a bit of avocado oil. Remove veggies from oven, add diced onion, and toss. Season with salt and pepper and return to the oven for another 20-30 minutes, until they reach the desired level of caramelization.