Celery and Potato Soup for 4

Scaled to serve 5

62.5 g of margarineheattosssimmer 30minblend
562.5 g of celerycut into 1.5cm pieces
343.8 g of potatoespeeled, cut into 2.5cm cubes
1125.0 ml of chicken stock
1.2 bouquet garni
1.2 salt and pepper