Fried onions are a food item and cooking ingredient made by cooking chopped onions on a range or fire. This requires level 42 Cooking and grants 60 experience points. There is a chance players may burn the chopped onions and obtain a burnt onion instead.
It is more commonly used as an ingredient to create mushroom & onion topping by combining it with fried mushrooms at a Cooking level of 57. This does not grant any Cooking experience, but in turn mushroom & onion can be used at level 64 with a potato with butter to create the highly desirable mushroom potato for 55 experience.