AKA allium cepa.Frozen onion rings slices and dices.Onions, offer a healthy way to give your meals more flavor and provide nutrients without adding many calories.For cooked onions, the more finely you chop the onions, the stronger their flavor will be. You can pickle red onions and add them to sandwiches or serve them as a side dish, use them raw in salads and salsas or top a pizza with them and other vegetables. Red onions can be used in place of white or yellow onions in most recipes.