In a pot, on olive oil, braise the sliced leek. Add butter and the chicken breast cut into cubes. Fry for about 5-7 minutes, stirring occasionally.
Add peeled and diced potatoes and fry for another 3-4 minutes. Season with salt and pepper, add carrot with peas (without thawing), fry for 2-3 minutes.
Pour in hot broth, bring to a boil. Reduce heat, cover and cook for about 20 minutes until potatoes are tender. Remove from heat, add milk and mix.
Add a few tablespoons of soup broth to the sour cream, constantly stirring. Pour into the pot with the soup and mix. Add chives and if necessary, gently reheat.