There was once a time when I thought espresso was disgusting. Espresso, I thought, was a quaffable form of tar, consumed mostly as proof of inner fortitude. Then I went to a café that served proper espresso. The drink was bitter, of course, but it was also sweet, nutty and citrusy. I realized then that espresso could be incredible.
Later, I was given an espresso machine. It was a low-end Breville, a brand from Australia, and it made atrocious espresso. I tried to make it better. I bought ground coffee from a reputable roaster, and I tried to tamp it like a professional. Yet every time, the result was the same: a shot of dull brown liquid, obnoxiously bitter, with crema as flimsy as Toronto's crumbling Gardiner Expressway. Maybe, I thought, it was only homemade espresso that was consistently terrible.
Well, I was wrong again. One day I was chatting with Sam James, widely recognized as one of the best baristas in Toronto, and I happened to mention my home espresso setup. I told him that I buy my coffee pre-ground. Immediately he said that if I'm truly concerned about good espresso, I should grind my coffee à la minute. A coffee bean's most important tastes and aromas dissipate, he said, within a few minutes of being ground. I could easily have good espresso at home – even with my rudimentary machine – if I was willing to shell out on a high-quality grinder.
Luckily, he had a spare grinder at one of his shops. I bought it from him for a couple hundred dollars. It's a Mazzer Super Jolly, an industrial quality burr grinder that normally retails for around $1,000. I could open a coffee shop with it if I wanted to. Immediately my espresso was exponentially better, and after a bit of tweaking, it became great. It was complex and slightly viscous, with crema as rich as the head on a pint of Guinness.
There are a number of reasons for the dramatic improvement. For one, coffee should always be made with just-ground beans. You'll never get subtleties from coffee that has been ground hours or days or weeks prior. But espresso is also fickle. It requires a very fine, uniform grind, and the consistency of the grind needs to be continually adjusted to compensate for various factors, including humidity. (James says that at his shops, baristas often adjust the grind six to 10 times per day). The precision needed for a proper grind is high, so a quality machine is key.
Espresso machines are simple, for the most part. They push hot water out of a shower head. Some of them look fancy, but a cheap one can perform the function fairly easily. A grinder, on the other hand, is a complex piece of machinery with moving parts. If it generates too much heat, it will damage the beans. And the grinds must be even and minutely adjustable. All of this requires artful engineering.
There are lots of inexpensive grinders out there, and these are a waste of money. They're cheaply built and they'll create grinds that are both chunky and as fine as dust in one go. For French press or drip coffee, grind consistency is less important, so a cheaper grinder – a hand-operated grinder, even – is probably just fine.
If you're talking about espresso, though, even a top-notch machine can't do its job if the grinder isn't up to par. Yet a cheap machine paired with a good burr grinder (as opposed to a blade grinder) yields great results.
It's a basic fact of life that good espresso is going to cost money, so spend it where it counts. A Mazzer Mini is probably the bare minimum as a starting point, but a Mazzer Super Jolly is better (currently there's a used one on eBay for $500).
Also, properly roasted beans are crucial. Many roasters intentionally over-roast their beans to ensure consistency; if the beans are black and oily, avoid them. Because drinking espresso should never be an exercise in stoicism.