Preheat oven to broil. Place chiles on a baking sheet and roast chiles under broiler, turning with tongs until skin is blistered. Seal in plastic bag for 30 minutes. Skin chiles. Slit them lengthwise to remove veins and seeds. Set aside.
Heat a 12-in sauté pan over medium heat and melt butter. Add onions and garlic and sauté for 3 - 4 minutes. 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.
In the bowl of a mixer, beat egg whites until stiff. In a separate bowl, beat egg yolks and fold into whites.
Dip stuffed chiles in flour and then in beaten eggs.
In another 12-in. sauté pan, heat vegetable oil over medium-high heat. When a drop of water added to oil sizzles, start frying chiles until golden brown.
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.