In a wok or large fry pan stir fry the prawns with about a teaspoon of oil and some season with salt and pepper just until it turns pink. Take out and set aside.
In the same wok add in all the oil and the onions and garlic. Cook until fragrant and then add in the butternut squash and cook until it's soft, about 5 to 7 minutes. Then add in the beans and carrots and cook for another 2 minutes to heat through. It's nice to keep them crunchy for texture. Add the prawns back in and stir fry for a minute.
Make the Sauce
In a large bowl place in all the ingredients except for the chopped cashews. Mix well until fully incorporated. You can also use a mini blender to make it easier.
Put it all together
Take a wrap and place a lettuce leaf on it and spoon about 2 tablespoons of the filling. Then take the bottom corner and fold it up and fold the corners over. You may need a tooth pick to secure it. Sprinkle some cashew nuts on top and serve with the sauce on the side.