Coat a 2-qt. baking dish with cooking spray; add potatoes and 1 tablespoon onion. dissolve bouillon in water; pour 1/2 cup over potatoes. In a large bowl, combine the taco seasoning, milk, 1/4 cup salsa, oats, egg substitute and remaining onion; crumble turkey over mixture and mix well.
Spread over potatoes. Combine remaining salsa and chicken broth; pour over the turkey mixture. Bake, uncovered, at 350° for 1 hour or until a thermometer reads 165° and meat is no longer pink.