Chop the onion into small pieces.

Melt the butter in a large pot or kettle over medium heat.

Add the chopped onion to the pot and cook until slightly wilted.

Dice the potato into small cubes.

Dice the carrots, celery, and string beans into small pieces. Combine to measure 2 cups.

Add the diced potato and other diced vegetables (carrots, celery, string beans) to the pot.

Pour in the soup stock and water.

Bring the mixture to a boil, then reduce heat and simmer until the vegetables are tender.

Add the green peas and tomato juice to the soup.

In a separate small bowl, blend the flour with the sour cream until smooth.

Ladle a small amount of the hot soup into the sour cream mixture and stir to temper it.

Pour the tempered sour cream mixture into the main pot of soup and stir well to combine.

Bring the soup back to a gentle boil, stirring constantly to prevent sticking.

Season the soup to taste with salt and pepper.

Stir in chopped parsley or dill for added flavor.

Serve hot.