Heat olive oil in a skillet over medium and heat grilled portabello mushroom until warm. Remove and set aside. In the same skillet, cook the apple, celery, onion, sage, sea salt and pepper for 5 minutes. Add the garlic and cook for about 30 seconds. Pour in the vegetable stock and kale. Mix the ingredients until the kale has been submerged in the broth. Bring to a boil and reduce heat; let simmer for 15 minutes or until kale is tender. Once kale has cooked to a tender texture, remove from heat and let set for 5 minutes. Pour kale mixture into a blender container and puree. Add vinegar, mustard and coconut milk; process until all ingredients are pulverized. Serve in bowls. Top with the minced mushroom.