Get your butcher to take the legs and the breasts off of the bird for you but keep the rest of the bird as you will need this to make your stock.
To your boiling water add your bird carcass, peppercorns and onions. Turn down the heat and simmer for 30 minutes.
Whilst your stock is cooking take the pheasant pieces and coat with the flour. Put a heavy bottomed frying pan on the heat and add olive oil. When the oil comes up to temperature fry the pheasant pieces until golden.
Put the pheasant pieces to one side and pour half the red wine into the same frying pan to de-glaze it. Let this reduce by half.
In another frying pan add the butter and olive oil. Add the leek and mushrooms then cook on a low heat for 7 minutes and season to taste.
Take a casserole dish and put the leek and mushroom mixture in followed by the pheasant pieces and the reduced red wine. Pour in the remaining red wine and slowly ladle in the stock.
Prepare the asparagus by snapping it at its natural breaking point and slicing it in half. Add this, the peas, potatoes and the boquet garni to the casserole dish and top up with the stock until all the vegetables and pheasant are covered.
Put a lid on the casserole dish and place in the oven for 1 hour. After 1 hour check the casserole dish and if needed add more stock and seasoning then cook for a further 30 minutes.
Clean the carrots and add to a large saucepan of boiling salted water, boil for 8 minutes then add the corn kernels and boil for a further 4 minutes.
Take 2 large rustic bowls add a good portion of pheasant casserole dish into each then spoon in the carrots and corn kernels. Serve with freshly baked bread and enjoy.