Espresso, a perfectionist’s guide  

An Italian espresso is a polyphasic beverage prepared from roasted and ground coffee and water alone, constituted by a foam layer with a partiucular “tiger tail” pattern, on top of an emulsion of microscopic oil droplets in an aqueous solution of sugars, acids, protein-like materials, and caffeine, with dispersed gas-bubbles and solids … The distinguishing sensory characteristics of italian espresso include a rich body, a full fine aroma, and equilibrated bitter-sweet taste with an acidic note, and a pleasant lingering after-taste, exempt from unpleasant flavor defects.

ERNESTO ILLY

“The best” is not a thing. It’s a reward for winning the battle fought between minutiae and desire. Reasonable people would probably not spend the time to read all six of the linked pages, buy expensive equipment, develop and refine a proper technique, and slowly build up the necessary experience required to make an absolutely perfect 2.5 ounce drink. But who cares about reasonable people?

If you’re an unreasonable person, the rabbit hole is endlessly deep. The linked article is only the beginning.

See also: CoffeeGeek’s The Milk Frothing Guide