You're going to pay a few extra bucks, but it won't matter. Unlike other gourmet burgers that cost the same for a half-pound of Angus chuck drizzled in exotic toppings, the chuck at Mesa comes from the reputable Niman Ranch, home of happy, grass-fed cows. You will taste the difference. You'll bite into a burger that's the opposite of hormone-treated, corn-fed meat, one that's aromatic and near-sensual. Mesa's decision to purchase locally and use sustainably raised animals to create their massive gourmet feats makes us happy. And so do the avocado, Applewood-smoked bacon, caramelized onions, house-made aioli and crispy, herb-dusted fancy fries (pommes frites) that complement the best burger in town.