Mushroom - Cooking like a Boss

Quantity recently doubled to reflect the lack of wartime rationing! Tom may not like the concept of mushrooms.

70g 0.07kg 0.154lb 2.47oz margarine for onion	melt	cook til soft and translucent	sweat 8 minutes	simmer 1hr with lid	blend until conceptually smooth
2 ¹⁄₂ onion	chopped
850g 0.85kg 1.87lb 30oz button mushrooms	wash and quater
117 ¹⁄₂g 0.117kg 0.259lb 4.14oz margarine for mushrooms
2 ¹⁄₂tsp 0.013l 12 ¹⁄₂ml ⁵⁄₆tbsp 0.053cup 0.022pint parsley
2 ¹⁄₂l 2500ml 166 ²⁄₃tbsp 500tsp 10.6cup 4.4pint chicken stock