What can you use instead of cognac?
Most alcohols can be substituted with a fruit juice of your choice. There is nothing with exactly the same flavour as alcohol but fruit juices function nearly the same way in most dishes (the most notable exception, of course, being flambe dishes–gotta have alcohol for those). For cognac, I usually use apricot juice. If you really need the acidity of an alcohol, cut juice with a little rice vinegar, anywhere from 1/2 to 3 tablespoons per cup.