By Kirk Miller Welcome to Show Me the Proof, a column where we pose big questions to the booze world and get drinks experts to argue the finer points. In our second column, we’re tackling the controversial question, “How can we improve the margarita?” (and Happy National Margarita Day if you’re reading this on Feb. 22). It’s easy to love a margarita: Simple to make, it’s also a crowd-pleasing mix of tangy, sweet and (in some cases) salty. And, in this past year of to-go cocktails, the drink’s been ubiquitous on menus. I just wish the drink was … better. I don’t blame the cocktail itself. If ma…