Place the porcini mushrooms in a bowl, cover with boiling water and leave to soak for 30 minutes.
Drain and reserve 100ml of the soaking liquid. Chop the porcini mushrooms into small pieces.
Heat 50g of butter in a frying pan over a medium heat and add the shallot. Fry for one minute until softened.
Add the portobello mushrooms, thyme and chopped garlic. Fry, stirring regularly, for 4-5 minutes then add the chopped porcini along with the reserved soaking liquid. Continue to cook for about 2 minutes.
While the mushrooms are cooking, add the remaining 25g of butter and 1 tbsp of olive oil to a small frying pan and add the pigeon breasts. Fry on each side for 2-3 minutes, remove from the pan and allow to rest.
Add the crème fraiche to the mushrooms, season generously, then add the Parmesan, parsley and lemon juice. Carefully spoon onto the toasted sourdough slices.
Slice the pigeon breasts and place on top of the mushroom bruschetta. Finish off with a little more grated parmesan sprinkled over.