Elephant garlic looks like garlic (in giant form), tastes like garlic and smells like garlic yet it is said to be more closely related to leeks. Methinks that may be just because somebody said so. Either way both leeks and garlic are in the same genus (Allium), as are onions, shallots, ramps etc.
I roasted elephant garlic and an onion with olive oil. Partway through baking I made a few cuts into the large cloves to speed up the cooking process.
The roasted garlic and onion went into a pot along with a can of coconut milk and brought to a simmer. It was then blended with an immersion blender and run through a sieve to strain out any caramelized bits of garlic which might be bitter.
Thinly sliced carrots, thinly sliced celery, dried kaffir lime leaves and a dried Kashmiri chili were then added.
I seasoned the soup with kosher salt but added too much so I added thinly sliced red potatoes to compensate.
In the course of cooking and tasting I determined that the lime leaves had made sufficient contribution and removed them.
I was a bit concerned that a soup with garlic as a major flavor contributor might be overpowering, but it was not.