In a large saucepan, heat the olive oil on medium heat. Cook the onion, celery and garlic until the onion are fragrant and translucent. Add the potatoes and asparagus and mix well.
Add in the vegetable broth and bring to a boil. Reduce heat and allow to simmer until the vegetables are soft.
In batches, puree the soup in a blender until smooth. Pour back into the saucepan.
Add in the pepper and lemon juice, adding more if desired. Continue to cook on low until ready to serve.
When ready to serve, scoop into bowls and top with coconut milk and cayenne pepper, if desired.