Remove your grouse out of the packaging, pat dry and bring to room temperature.
Pre heat a griddle or heavy based frying pan until it sizzles when you add a drop of oil.
Season the breasts with sea salt and black pepper just prior to cooking.
Add a knob of butter and a little oil to the pan then sear the breasts on both sides over high heat, a couple of minutes in total until well coloured.
Press the breasts with your thumb, they should have a slight spring to touch and a core temperature of 52°C before resting.
Leave to rest in a warm place for a couple of minutes before carving at a angle into thin slices.
Method for the Mushrooms
Sauté the mushrooms in a knob of butter with the shallot and garlic until all the juice evaporates.
Add a splash of madeira and cook until all moisture has gone.
Pop onto a clean chopping board and roughly chop the mushrooms.
Season to taste and add a few fresh thyme leaves, keep warm.
To serve
Serve the mushrooms piled onto toasted sourdough with thin slices of grouse layered over, a scattering of mustard cress and the red wine sauce around. I like to drink a light red such as a Pinot Noir with this dish.