1. Chop and discard the woody portion of asparagus. Then, chop the remaining, leaving out 2-inch long strip from the top.
2. Place a large sauce pan on medium high heat, pour oil and drop leaks in it. Sauté for about 2 minutes or until they caramelize lightly.
3. Add asparagus, garlic, celery root, parsley, rosemary, chilli flakes, and lemon juice.
4. Pour the water and season with salt and pepper. Mix well.
5. Add chili flakes and squeeze in the lemon.
6. Cover with lid, and allow it to simmer for 10 minutes or until vegetables are nice and tender.
7. With a hand blender,blend until smooth.
8. Now, drop the tender asparagus tips in pan. Cook for about 2 minutes. Remove from heat.
9. Serve soup at room temperature with a dollop of cream.