Chop leeks, parsnip, and potatoes.

Grate ginger and crush garlic.

In a soup pot, combine leeks, parsnip, potatoes, ginger, garlic, olive oil, and water.

Cook over low heat, covered, for 30 minutes, stirring occasionally and adding water if needed.

Add fish stock, water, and salt to the pot.

Bring to a gentle boil and simmer, partially covered, for 45 minutes.

Preheat oven to 400°F.

Cut ciabatta into cubes and drizzle with olive oil.

Bake croutons for 10 minutes, or until golden, and sprinkle with sea salt.

Cool soup for 10 minutes.

Transfer 3 cups of soup to a food processor with parsley and blend until smooth.

Return blended soup to the pot and mix it in.

Puree more soup for a thicker consistency.

Reheat soup, adding cream if desired.

Gently add smoked fish and serve hot, dusted with paprika and topped with croutons.