Heat the vegetable oil in large pan (a wok works well for all soups). Use a blender to semi-puree the onion, add to the oil and cook on a medium heat until softened.
Add the diced potato and a knob of butter. Cook for a further 5 minutes.
Add the stock and simmer for 15 minutes or until the potato is soft. If you want to use the edible parts of the broccoli stalks add them here.
Add the broccoli heads and cook for a further 10 minutes. Blend the soup until it is creamy and return to the pan.
Stir in the cheese until completely melted and simmer gently for 5 more minutes.
Season with the black pepper and serve with crusty French bread and butter.
To change the cheese simply replace gram for gram. Stilton and Saint Agur Blue work best as other types of blue cheese can sometimes be too salty.
If desired add a stick of chopped celery and/or a chopped leek at stage 2.
Blue cheese is a general classification of cheeses that have had cultures of the moldPenicillium added so that the final product is spotted or veined throughout with blue, blue-grey, blue-green, or blue-brown mold and carries a distinct smell, either from that or various specially cultivated bacteria. Some blue cheeses are injected with spores before the curds form, and others have spores mixed in with the curds after they form. Blue cheeses are typically aged in a temperature-controlled environment such as a cave. Blue cheese can be eaten by itself or can be spread, crumbled or melted into or over foods.