How can you have chili without onions? Or, frito pie if you will? Or, hot dogs? Or, blooming onions? What WiLl YoU dO wItHoUt OnIoNs? But, PsYcHeDeLlIc MuShRoOmS for the win!
Replace onions with shallots and you don't miss that much. In some places it would probably be a pretty solid upgrade, actually. Chives are actually a pretty solid upgrade on green onions, usually, if you can dice up enough of them. I don't eat enough truffles to know if you could sub them out for mushrooms, but maybe?
What are you doing to your steak that it needs toppings? Also, mushrooms are disgusting and onions are delicious.
What the **** is mushroom salsa? I love my mushrooms but I'm gonna rock with onions AND bell peppers everytime.
Corn smut is a plant disease caused by the pathogenic fungus Ustilago maydis that causes smut on maize and teosinte. The fungus forms galls on all above-ground parts of corn species. It is edible, and is known in Mexico as the delicacy huitlacoche; which is eaten, usually as a filling, in quesadillas and other tortilla-based foods, and in soups.
While researching this topic, I learned that the little white mushrooms at the grocery store and portabella mushrooms are the same thing, the white ones are just not matured yet. Crazy. I have not tried most of the mushrooms in the world, just those portabella's in both stages and the Japanese ones that run into problems with the language filter. I have heard good things about the chicken of the woods variety (tastes like chicken). So, based on my limited experience, onion.