Celery and Potato Soup for 4

Scaled to serve 10

125.0 g of margarineheattosssimmer 30minblend
1125.0 g of celerycut into 1.5cm pieces
687.5 g of potatoespeeled, cut into 2.5cm cubes
2250.0 ml of chicken stock
2.5 bouquet garni
2.5 salt and pepper