To flavor the meat, I opted for a spice paste. Minimalists use a combination of salt, cumin, and garlic. At the other end of the spectrum are recipes that call for a laundry list of ground spices and chili powders. To produce the complexity of the latter via the short ingredient list of the former, I popped open a can of chipotles (smoked jalapeños) in adobo sauce. This powerhouse ingredient would contribute spicy, smoky, and savory notes. I added cumin, oil, and a little salt to the minced chipotles to make a paste. After evenly coating the steak with the ruddy mixture, I headed outside and lit a chimney full of charcoal.

Grilled directly over the coals (a gas grill works well, too), the thickest part of the steak was medium‑rare (125 degrees) in 10 minutes. After letting the meat rest, I thinly sliced it against the grain. The chipotle paste was a keeper, but the thinner areas of the steak were overdone. What’s more, the meat was unevenly browned and didn’t have much grill flavor.

For my second try, I sliced the steak into thirds lengthwise. This separated the tapered edges from the thicker center so I could grill each piece to the proper doneness. These narrow strips, once sliced, would also fit nicely into 6-inch tortillas.

The mediocre browning in my first test had been a result of the steak buckling as it cooked; the bottom of the steak (closest to the heat source) cooked more quickly than the top, which caused its fibers to shrink and gave the meat a concave shape. Frequent flipping helped the top and bottom shrink at about the same rate, so the steak stayed flat and browned evenly.

As for the flavor deficit, I knew that cooking on a grill doesn’t necessarily guarantee grill flavor. Many of the compounds responsible for this flavor are created when fat and juices drip onto the coals, vaporize, and waft up and condense onto the food. If I wanted deep grill flavor, I needed drippings. And I had been trimming away a main source: the fat on the steak.

I grabbed another steak, trimmed the thicker fat deposits to 1/8 inch, and left the thinner ones in place. I applied the chipotle paste and grilled the steak, flipping it every 2 minutes. Rendered fat dripped onto the coals, causing small flare-ups that brought with them a smoky, meaty flavor that tasted like success. This was an A-plus steak.

Since I had a hot grill, I decided to do the rest of the cooking outside as well. Inspired by the charred scallions that often adorn tacos al carbón, I decided to whip up a grilled scallion salsa. Along with the scallions, I threw some jalapeños onto the fire, making a note that next time, I could grill the chiles alongside the steak since they cook in about the same amount of time. This would not only be more efficient but also infuse the chiles with the flavors of the vaporized drippings. Finally, I blistered tortillas on the hotter side of the grill until they picked up a toasty, popcorn‑like aroma and then wrapped them tightly in foil so that they would stay warm and soft.

Back inside, while the steak rested, I seeded and finely chopped the jalapeños and coarsely chopped the scallions. I combined them in a bowl with a squeeze of lime and a sprinkle of salt, assembled some tacos, and rounded up my colleagues. This time no one doubted that the rosy steak had come from the grill. They also praised the lively salsa but felt that the two elements were too disparate. I reached for the canned chipotles and stirred just enough of the savory adobo sauce into the salsa to tie its flavor to the steak. That, along with dollops of rich crema and a few more squirts of lime, brought everything together.