In small skillet, heat 2 Tbs of the oil over medium heat. Fry chilies a few seconds on each side or until puffed and brown; do not let them burn. Drain on paper towels.
In spice grinder, grind chilies, oregano, cumin and salt to a coarse powder.
With sharp knife, score skin side of duck breasts in a series of parallel cuts 3/4 inch apart, without cutting into meat. Make a second series of parallel cuts perpendicular to the first to form crosshatch pattern. Rub chipotle powder on both sides of duck breasts; refrigerate, covered, 30 minutes.
To make Pineapple Salsa, brush pineapple and onion slices with oil. Grill over medium-hot gas or charcoal grill about 8 minutes, turning occasionally, until browned and slightly soft. Cut into 1-inch pieces, discarding pineapple cores. In food processor, pulse pineapple and onion with remaining ingredients until coarsely chopped (makes about 2 cups).
Place breasts skin side down in heavy nonstick skillet large enough to hold them comfortably in one layer. Cook over medium heat about 8 minutes or until fat runs out and skin is golden-brown and crisp. (Some breasts may brown more quickly than others; remove each breast as it is done.)
Transfer duck breasts to medium-hot gas or charcoal grill, skin side up; grill about 8 minutes for rare, 10 minutes for medium-rare and 12 minutes for medium.
Let breasts rest 3 to 4 minutes before slicing.
Cut each breast crosswise on a slight angle into 4 to 5 slices about 1/2-inch thick. Serve with Pineapple Salsa.
Tips:
Serve with mashed sweet potatoes seasoned with roasted garlic pur?e. Wear plastic gloves when handling chilies.
