Given the task definition and input, reply with output. In this task, you have to identify the named entities (NER) which are the ingredients required given its directions. Named entities are the names of the items without their quantity.

Preheat oven to 400., Slice onion and lemon., Place ribs in 9x12-inch baking dish., Place onion slices on each rib., Place a lemon slice on each rib., Bake ribs at 400 for 1/2 hour., Remove lemon slices and pour (or brush) barbecue sauce over ribs., Reduce heat to 350 and cook for one hour, basting every 15 minute.
country-style pork ribs, onion, lemon, barbecue sauce