India pale ale was born of necessity. How to preserve Britons' beloved beverage during its long voyage to the far-flung corners of the empire? The solution was elegant in its simplicity, its genius so profound that it has become a rallying cry for craft brewers across America: "Add more hops!" O'Fallon 5-Day IPA — so named because the beer sits atop dry hops for five days during the fermenting process — might not be the hoppiest beer around, but it's a beautiful example of this essential style. The color is a rich amber, the nose floral. The flavor is explosive: malty sweetness and then that unmistakable hoppy rush of citrus and spice. It is delicious anytime, anywhere, but should you find yourself at Iron Barley (5510 Virginia Ave.; 314-351-4500; www.ironbarley.com) in Carondelet or Dressel's (419 N. Euclid Ave.; 314-361-1060; www.dresselspub.com) in the Central West End, try it in cask-conditioned form. Held at cellar temperature, the beer's flavor is pure and utterly perfect.