Roast chiles under broiler, turning with tongs until skin is blistered. Seal in plastic bag for 1/2-hour. Skin chiles. Slit them lengthwise to remove veins and seeds. Set aside.
Sauté onion and garlic in butter. Add ground pork and cook until no longer pink. Add tomato purée, cinnamon, raisins, almonds, sugar, salt and pepper. Stir in peaches and pears and simmer until thick. Stuff prepared chiles with filling and chill for 1 hour.
Beat egg whites until stiff. Beat egg yolks and fold into whites. Dip stuffed chiles in flour and then in beaten eggs. Fry in vegetable oil. Serve hot with cold Walnut Sauce.
In a food processor, grind together walnuts and almonds; mix with cheese. Add enough milk to make a thick sauce; add sugar to taste. Cover and chill until ready to use.