Coarsely chop the bacon; peel and chop the onions or shallots.
2
Place 1 tbsp oil in a deep oven proof frying pan or shallow flameproof casserole dish and cook the bacon on the floor of the roasting oven for 7 to 10 minutes until crisp. Remove with a slotted spoon.
3
Add 1 tbsp oil to the pan and cook the mushrooms on the boilingplate for 4 to 5 minutes.