Preheat oven to 200/180. In a large roasting tin, toss together the butternut squash with half of the oil and roast for 20 mins.
Meanwhile, heat remaining oil in a large frying pan over medium heat and fry the onions for 10 mins until softened, add the peppers and cabbage with spices and a splash of water. Cook for 10mins until softened. Stir in the beans and cooked butternut squash.
Meanwhile, peel and mash the avocado. Mix in lime juice, spring onions, coriander and chilli flakes. Season to taste.
Add the tortillas to the oven to soften. Fill tortillas with veggie mix and top with chopped tomatoes, cheese and Greek Yogurt/sour cream.