Turmeric Roasted Sweet Potato and Macadamia Soup

Name: Turmeric Roasted Sweet Potato and Macadamia Soup
Prep time: 10 min
Cook time: 1 h 10 min
Total time: 1 h 20 min
Cuisine: American
Ingredients: 2 medium red onions (peeled and quartered); 2 pounds orange sweet potatoes, peeled and cut into chunks ((about 6 1/2 cups)); 1 tablespoon extra-virgin olive oil; 1/2 teaspoon Kosher sea salt (plus more to taste); 8 cups vegetable broth; 2 teaspoons minced fresh ginger; 1/2 teaspoon ground turmeric; Pinch of cayenne pepper (plus more to taste); 1/4 cup unsalted macadamias (70g ); Fresh lime wedges (to serve); 2 tablespoons finely chopped fresh cilantro (to serve); Optional chopped macadamias, for garnish