Tarragon chicken with creamy vegetables

Ingredients

• 750 g new potatoes (scrubbed)
• 4 large carrots (peeled)
• 4 skinless chicken breasts ((about 150 grams/5 oz each))
• 1 tsp olive oil
• 1 tbsp lemon juice
• 1/4 cup fresh tarragon (chopped, or 2 teaspoons dried tarragon)
• 3/4 cup light sour cream
• 2/3 cup diluted salt-reduced or homemade chicken stock
• 1 garlic clove (crushed)
• 4 scallions (finely chopped)