How important are olives in Ropa Vieja? Can I substitute/omit them? I'm looking to make some Ropa Vieja in my crock pot but I've got a picky eater who refuses to touch anything with olives or capers in it. My concern is that something about the briney/acidic nature of the olives helps break down the otherwise lackluster flank steak in the dish. Is this the case or are the olives something that can be omitted without consequence? Is there an acceptable substitute?
I've seen recipes that stir in the olives at the end of the cooking time.  You can leave them out with no ill-effects. Olive and capers are not that easy to substitute for.   Maybe a dash of vinegar would add the acidity that the dish needs.