Prepare chicken stock with cube and 0.5 lt water.
Add split peas and let it simmer gently for 60 minutes.
Preheat the oven to 180 degrees Celsius.
Clean the celeriac and carrot and chop into cubes.
Rinse the celery leaves and finely chop them.
Rinse and slice leeks in half lengthwise. Slice the halves into thin strips.
Add celeriac, celery leaves, leeks and carrot to the soup.
Mix chicken thighs with sunflower oil, black pepper and grill them for 15 minutes in the oven.
Let it cool down and slice in pieces.
Add chicken to the split pea soup and flavour with black pepper.