Remove tops and seeds from 3 peppers; cut peppers in half lengthwise.
Cook in boiling salted water in saucepan for 8 to 10 minutes or until tender.
Drain peppers; cool and peel.
Cut beef tips into 1/2-inch cubes.
Saute beef and chopped onion in shortening until lightly browned.
Add pecans, raisins, 1/2 tea- spoon salt and chili powder.
Spoon beef mixture into pepper halves.
Roll peppers in flour, coating well.
Beat egg whites until stiff but not dry.
Add 3 tablespoons flour and 112 teaspoon salt to egg yolks; beat until thick and lemon colored.
Fold egg whites into egg yolk mixture.
Drop egg mixture by 1/2 cup- fuls into shallow hot fat in skillet, spreading to make circles slightly longer than peppers.
Cook until egg mixture begins to set.
Arrange pepper halves in cir- cles; cover each pepper half with remaining batter.
Cook until underside is browned; turn and brown remaining side.
Slice remaining pepper; saute sliced pepper and sliced onion in butter.
Remove pepper and onion from skillet.
Add 1 1/2 tablespoons flour to pan drippings, blending until smooth.
Add tomato sauce and 1 cup water.
Cook, stirring constantly until thickened.
Add sugar and 1/2 teaspoon salt.
Add cooked peppers and onion.
Place Chiles Rellenos in serving dish; spoon hot sauce over top.
Serve immediately.