Preheat oven to 350°.
Combine first 6 ingredients in a bowl. Divide the crab mixture evenly among chile halves.
Place stuffed chiles in an 11- x 7-inch baking dish coated with cooking spray.
Combine tomato and remaining ingredients in a saucepan; bring to a boil. Cover, reduce heat, and simmer 30 minutes or until onion is soft. Pour warm tomato salsa over chiles. Cover and bake at 350° for 45 minutes.