Celery and Potato Soup for 4

Scaled to serve 6

75.0 g of margarineheattosssimmer 30minblend
675.0 g of celerycut into 1.5cm pieces
412.5 g of potatoespeeled, cut into 2.5cm cubes
1350.0 ml of chicken stock
1.5 bouquet garni
1.5 salt and pepper