Chop all vegetables (broccoli, cauliflower, onion, garlic, celery, carrot, potatoes) into small pieces.

Place chopped vegetables in a pot.

Add chicken stock to cover the vegetables.

Add parsley, cayenne pepper, salt, and pepper to taste.

Bring to a boil, then reduce heat and simmer until vegetables are soft (approximately 30-40 minutes).

Let the soup cool slightly (about 15 minutes).

Transfer soup in batches to a blender.

Add 1 spoonful of sour cream to each batch during blending.

Blend until smooth.

Pour puréed soup back into the pot.

Reheat gently.

Serve hot.

Garnish with dried bread sticks or croutons if desired.