The phrase "sliced onions" refers to diced or chopped pieces of onion. Onions are a type of vegetable that are commonly used in cooking due to their pungent flavor and high nutritional value. When they are sliced, it means that the onion has been cut into thin strips or small cubes, making them easier to use in recipes without having to chop them by hand. Sliced onions can be used as a garnish, added to salads, stir-fried dishes, and many other culinary creations.