Coffee-Rubbed Steak Tacos with Pickled Red Onions

1. Place the red onions in a small heat-safe bowl. Combine the vinegar, water, sugar, and 2 tablespoons of salt in a small saucepan and bring to a boil. Pour the liquid over the onions and let them sit at room temperature for 30 to 45 minutes, until the onions turn bright pink in color.

2. Preheat the oven to 400°F. Stir together the brown sugar, chili powder, coffee, paprika, remaining 2 teaspoons of salt, and the black pepper in a small bowl to combine. Meanwhile, heat the olive oil in a large, oven-safe skillet over medium-high heat. Rub the coffee mixture all over the steaks, covering completely. Put the steaks into the hot pan. Sear the steaks for about 2 minutes per side, until a golden brown crust forms. Transfer to the oven and cook for 5 to 7 minutes, until the meat registers 125°F on a meat thermometer. Transfer the steaks to a cutting board and let them rest for 10 minutes.

3. Slice the steak against the grain into thin slices. Arrange the steaks in the corn tortillas. Top each with some of the pickled red onions, cotija cheese, and a squeeze of lime juice.