Heat oil in large pot over medium heat. Add onion, celery, carrot, ginger and sweet potato. Saute 5 minutes or until veggies start to soften. Add in apple, curry powder, garam masala, turmeric and cinnamon; saute another 5 minutes.
Add in red lentils and broth. Bring to a boil, reduce heat to simmer, partially covered, for 30 minutes and up to 2 hours.
Puree soup with a hand held blender (or in batches with stand up blender) until smooth. Season with salt to taste. Return soup to pot, add coconut milk and heat on low until ready to serve.
I’ve used ½ cup apple cider in place of apple, so if you have some go for it!