Combine 1/2 cup coffee liqueur, espresso powder, 3/4 teaspoon chili powder, dried oregano, brown sugar, 1/4 teaspoon salt, and 1/4 teaspoon black pepper. Pat steak dry and place it in a resealable bag. Add marinade and coat the steak evenly. Refrigerate for at least 1 hour, preferably overnight.

Let steak come to room temperature for 30 minutes before grilling. Remove steak from the marinade and discard the marinade. Pat the steak dry and season with an additional 1/4 teaspoon each of salt and pepper.

Preheat the grill to medium-high heat. Lightly oil the grill grates. Grill the steak for approximately 8-10 minutes, turning halfway through. Cook until the internal temperature reaches 130°F (54°C) for medium-rare. Rest for 10 minutes before slicing.

Heat olive oil in a skillet over medium heat. Add the garlic and cook for about 2 minutes until fragrant. Stir in the remaining 3/4 teaspoon chili powder, 1/4 teaspoon salt, and 1/4 teaspoon black pepper. Add the remaining 1/2 cup coffee liqueur and cook until reduced by half, about 2 minutes.