Whether you like espresso, cappucino, latte or one of the other versions of coffee nirvana, most of them are based upon an espresso pull and then have something added.
Lets clear something up right away, espresso is not a roast, it is a way of brewing coffee. The dark oily beans that you sometimes see are NOT necessary for an espresso. If you are limiting yourself to that then you are missing out on many of the nuances of this delightful drink.
An espresso is a coffee drink that is created by pumping close to boiling water under pressure through very finely ground coffee. This can be done via a pump, via a spring loaded lever or many other ways, but it is the process that is espresso, not the bean. One of my favourtie beans for espresso is Ethiopian Yirgacheffe that has been roasted medium. Not an oily bean in sight.
Espresso is also usually a fairly small drink – it isn’t your Extra LargeTims Double Double. By adding steamed milk you can create a Latte or a Cappucino, and make it a longer drink, but the basic espresso is usually only about I fl oz, so it is an intense burst of flavor.
The unique thing about the espresso process is that if you are using the right beans and they are ground exactly right then you will get a wonderful topping on your coffee that is a lightish creamy brown color with whisps of darker brown in it. This is called crema, and some beans produce a lot, and others very little, so a bit of internet research is called for. The crema is also what allows you to create latte art.
As a guideline if you are pulling single shots, then it should take your machine about 15 seconds to pour a 1 oz espresso. If it is faster than that – then make the grind a little finer, and if it is longer, then make the grind a little coarser. You can also compensate a little by tamping a little lighter or heavier. I tend to tamp very lightly and have a slightly finer grind, but others may choose differently.
The key to a good espresso is the grind and tamp. You need to have a very good grinder that is capable of grinding the coffee very finely and also very consistent. The last thing you want is some grounds to be almost dust and others to be Maxwell House size. Once you have ground it, you need to fill your portafilter and press it down evenly and that is where a good tamper comes in. If you are on a budget and are trying to figure out how to stretch your funds by have to make a choice between a cheap espresso machine and a cheap grinder, you will get much better espresso with the cheap machine and good grinder.