Beer-marinated chicken tacos

For the marinade:
1 cup dark Mexican beer, such as Negra Modelo
2 tablespoons dark sesame oil
1 tablespoon finely chopped garlic
1 teaspoon dried oregano
1 teaspoon kosher salt
1/2 teaspoon freshly ground black pepper
1/4 teaspoon cayenne
6 boneless, skinless chicken thighs, about 4 ounces each
For the guacamole:
2 ripe Haas avocados
1 tablespoon fresh lime juice
1/4 teaspoon kosher salt
6 flour or corn tortillas, 6 to 7 inches in diameter

1. To make the marinade: In a small bowl whisk together the marinade ingredients.
2. Rinse the chicken thighs under cold water and pat dry with paper towels. Place them in a large, plastic resealable bag and pour in the marinade. Press the air out of the bag and seal tightly. Turn the bag to distribute the marinade, place the bag in a bowl, and refrigerate for 2 to 4 hours, turning the bag occasionally.
3. To make the guacamole: Cut the avocados lengthwise around the pits, twist the halves apart, and remove the pits. Scoop the flesh into a medium bowl. Add the lime juice and salt. Using a potato masher or the back of a spoon, mash the ingredients together. Cover with plastic wrap, placing it directly on the surface to prevent browning, and refrigerate until about 1 hour before serving.
4. Remove the chicken thighs from the bag and discard the marinade. Grill the chicken thighs over Direct Medium heat until the meat is firm and the juices run clear, 8 to 10 minutes, turning once halfway through grilling time. Transfer the chicken to a cutting board and cut the thighs into thin strips.
5. Warm the tortillas over Direct Medium heat for about 1 minute, turning once halfway through grilling time. Pile the sliced chicken inside the tortillas. Top each taco with a spoonful of guacamole. Serve warm.