For example, I think any Italian joint should be able to whip up a spaghetti and meatballs on request, even if it's not on the menu.
Similarly, I think a Chinese restaurant should be able to ginny up a basic fried rice regardless of whether it's listed on the menu.
And I think it should be expected that a Mexican eatery would be able to make a simple beans and cheese burrito upon request.
Would those be asking too much?
What other dishes should always be available upon request, with or without mention on the menu?