Preheat oven to 350°. In large skillet, heat oil over medium-high heat. Add chicken and red onion; cook 8 minutes or until chicken is browned and onion is tender, breaking up chicken with side of spoon. Add salsa; cook 5 minutes or until slightly thickened, stirring occasionally. Makes about 4 cups.
With small, sharp knife, leaving stem end intact, cut lengthwise slit along 1 side of each pepper; remove seeds and membranes, being careful not to tear peppers. Stuff peppers with chicken mixture; place in 13 x 9-inch baking dish and sprinkle with cheese. Bake peppers 25 minutes or until heated through and cheese is melted. Makes 6 stuffed poblanos.
Serve stuffed poblanos garnished with yogurt, green onions, tomatoes and/or cilantro, if desired.