Split, skin, and bone chicken breasts.
Remove the filet, the small piece of meat that lies on top of each side of the breast, then remove the white ligament from each filet.
Cut each side of breast in half lengthwise and crosswise; including the filets, you should have 20 pieces.
Cut each piece through the thickness to within 1/4 inch of the other side; spread meat open so it forms a rectangle.
Cut each shrimp in half crosswise, then hit with the side of a heavy knife blade to mash slightly.
Cut ham in matchstick pieces.
To make each chicken roll, place 1/2 shrimp and 1 or 2 strips ham at the short end of each piece of chicken.
Roll up to form a cylinder.
Coat rolls on ail sides with cornstarch, then squeeze gently in your hand to seal.
At this point you can cover and refrigerate for as long as 8 hours, but bring to room temperature before cooking in deep fat.
To cook, combine flour, the 1/4 cup cornstarch, baking powder, and salt in a bowl.
Add water and blend until smooth.
In a deep pan, pour 11/2 inches salad oil and heat to 360° on a deep-frying thermometer.
Dip each chicken roll in batter, drain briefly, then place in hot oil.
Fry chicken without crowding, turning occasionally, until crust is golden brown and chicken is opaque
Remove with a slotted spoon, drain on paper towels, then arrange on a heatproof platter.
Keep warm in a 200° oven until all rolls are cooked.
Pour black bean sauce over chicken