Pearl onions and garlic cloves should be parboiled and peeled.
Preheat oven to 350 degrees F. In a heavy pot that can be covered, combine all the ingredients except the feta, walnuts and 1/2 cup parsley. Cover tightly and bake for 1 1/2 hours or more, until the meat is very tender. Lower the oven temperature during this time, so that the contents of the pot remain at a gentle simmer. Skim off the fat. Do not boil the sacue down; it should remain rather thin. Ladle the stew into a deep platter. Granish with feta, walnuts, and the remaining parsley.