Pour chicken stock and coconut milk into large Dutch oven or stock pot. Bring to a soft boil over low heat. Mix sausage, ground beef, beaten egg, breadcrumbs, ginger, cilantro, salt and pepper, red pepper flakes, onion and garlic. Form mixture into small bite-size balls. Add lemongrass, mushrooms and carrots to simmering stock, bring to gentle boil. Add meatballs and cook 5 minutes. Add spinach. Heat an additional 2 minutes.