Boil meat together with the leeks, carrot, onion, peppercorns, salt and pepper until tender. Take off meat and arrange in a platter. Reserve broth.
Roux: Mix butter and flour to form a paste. Set aside.
Sauce: In another pan, melt butter then add flour. Add mushrooms with water, onions, garlic and reserved broth, 1 cup at a time. Bring to a boil and thicken by adding roux. Add chives and fresh mushrooms.
Pour sauce on top of beef shank. Garnish with fried garlic and shallots. Cover with the grated carrots and zucchini.