Prep all ingredients per the instructions above.
In a bowl, whisk together olive oil, lime juice, garlic, cumin, crushed red pepper flakes, honey, and cilantro. Add the chicken and coat well with the marinade. Refrigerate for at least 30 minutes.
Heat olive oil in a saucepan over medium heat. Saute the garlic and onion until the onion begins to soften. Stir in the ground cumin, then add the black beans with their liquid. Season with salt and pepper and low simmer for about 15–20 minutes to develop flavor. Remove from heat and stir in chopped cilantro.
Make the guacamole: In a bowl, mash the avocado until smooth. Stir in cilantro, garlic, cumin, and lime juice. Season with salt. Refrigerate until ready to serve.
Preheat a grill or grill pan to medium-high heat.
Grill the chicken on both sides to an internal temperature of 160°F (74°C). Remove from heat and let rest for 2 -3 minutes before slicing or shredding.
Warm the tortillas: Heat a dry skillet over medium heat. Warm each taco shell for 20 seconds per side until soft and pliable.
Assemble the tacos by filling the taco shells with chicken, lettuce, cheese, cilantro, and avocado.
Pour sparkling water over lime slices and serve with ice if desired.
Serve tacos with tortilla chips, guacamole, black beans, and lime sparkling water.