In a large, heavy pan, heat coconut oil over medium-high heat. Sauté onions and potatoes until just softened, about 3 minutes.
Add garlic and saute for an additional minute. Add the garam masala spice and cook for 30 seconds.
Add the broth and bring to a boil; reduce to simmer, cover and cook for 20-25 minutes or until the potatoes are tender.
Add coconut milk and stir to mix. Transfer about half the soup to a blender or food processor and process until smooth (alternatively use a separate bowl with hand blender).
Return to the pot and add an additional ½ cup of broth if needed. Season with salt and pepper and top with cilantro.
Notes
Make ahead tip: This soup stores beautifully in the fridge for 5 days or the freezer for months.