Peel and chop the onion, carrots and parsnip. Wash and chop the celery and bell peppers. Cut the potatoes into bite-sized pieces.
Heat the vegetable oil in a large soup pot over medium heat.
Add the chopped onion, carrots, parsnip and celery. Fry until the vegetables soften, stirring occasionally.
Stir in the tomato paste and cook for another minute.
Add enough water to comfortably cover the vegetables and leave room for the pork and remaining ingredients.
Add the smoked pork bones and bring the soup to a boil. Reduce the heat and simmer for around 45 minutes.
Add the chopped bell peppers and potatoes. Continue cooking until the potatoes are tender.
Carefully remove the pork bones from the soup. Once cool enough to handle, remove the meat from the bones and discard the bones.
Return the pork meat to the soup.
In a separate saucepan, bring the Romanian borș to a boil.
Pour the hot borș into the soup and stir well. Taste before adding salt, as the smoked pork and borș may already provide enough seasoning.
Add the dried tarragon and let the soup simmer for another 5 minutes.
Turn off the heat and serve hot with a generous spoonful of sour cream.