Chef's note: You can easily make this a meal by adding your favorite protein such as cubed tofu, broccoli, mixed seafood or diced chicken.
Heat a large soup pot over medium heat, add the oil and sauté the onion for 2 to 3 minutes. Add the curry paste, turmeric, garlic and garlic salt; cook for an additional minute, constantly stirring to help release the essential oils in the spices. Add the fish sauce, coconut milk, diced tomatoes and stock. Bring to a gentle simmer and cook for about 10 minutes. Then add the kale, cooking just until it wilts. If the soup is thin, add instant mashed potato flakes to thicken as needed. To serve, ladle into bowls and top with chopped cilantro and chives.