Warm the olive oil in a large stock pot over medium heat until the olive oil shimmers. Add onions and cook until they soften and become translucent. Add cashews and cook until slightly brown. Stir in garlic and cook for about 30 seconds. Add the squash, broth, ginger, cumin, curry powder and turmeric. Stir and season with sea salt and black pepper to taste. Bring the soup to a simmer, and then reduce the heat to low, cover the pot, and cook until the squash can be pierced with a fork (20 minutes or so). Let soup cool for 15-20 minutes.