For the most consistent roast, you can’t beat a home coffee-roasting machine. Next best is the hot-air popcorn popper: It’ll keep the beans in constant motion, preventing scorching.
However, a simple stovetop setup can turn out reliable roasts with just a few pieces of equipment you likely already have: a cast-iron or heavy stainless steel pan (preferably with tall sides, such as a Dutch oven), a wooden spoon or a whisk, and a large colander. Coffee beans smoke while roasting, so if you don’t have a powerful kitchen exhaust fan, you’ll want a portable fan to direct smoke out an open window. Alternatively, perform this process outdoors on a grill.
1. Gather 1 1/2 cups of green coffee beans as well as a few roasted beans to use as a comparison for the color of the roast you hope to achieve.
2. Place the colander in the sink. The larger the colander’s holes, the better it will remove the bits of chaff clinging to the beans.
3. Preheat the pan over medium-high heat. You want the pan hot enough that a drop of water will dance across it and disappear quickly, but not so hot that coffee beans will scorch. If you have an infrared thermometer that can be aimed at a surface to gauge its temperature, shoot for between about 500 and 550 degrees Fahrenheit.
4. When the pan is hot enough, pour in the green beans and begin stirring immediately with your spoon or whisk, and don’t let up. Keep the beans in constant motion.
5. About 5 to 10 minutes after you put the beans in the pan, you’ll hear the “first crack” that signals the beginning of the progression from light to medium roast. It will sound like popcorn popping. When the continuous popping of the first crack begins to fade, you’ll have a light-medium to medium roast. If you continue until a fainter, second crack begins, you’re entering dark-roast territory. (Coffee beans expand as they roast. Occasionally, a bean may pop out of the pan, but using a pan with high sides will corral most of them.)
6. While you are listening to the beans, check their color as best you can without pausing in stirring. Work quickly when matching a roasting bean to your comparison bean. A second set of hands can be helpful during this process. In addition to color, Daniel Bowersox, head roaster at Z’s Divine Espresso in Lawrence, Kan., recommends waiting to remove the beans at least until the edges have slightly rounded and the mottled color you observed early in the roast has fully disappeared into an even color all over each bean.
7. When most of the beans in the pan have reached the roast color you’re aiming for, pour the beans into the colander and stir, stir, stir. Beans should be free of most of the chaff and cool to the touch within 2 to 3 minutes.
8. Store in an airtight container for use over the next several days, grinding the beans right before you start a pot of coffee. Freshly roasted beans are actually best 12 to 24 hours after roasting.
For other coffee roasting techniques: see How to Roast Your Own Coffee for an Amazing Cup.