Add the chicken, garlic, olive oil, lime, and spices, to a large bowl or zip-seal bag and stir or shake to combine.
Heat a large pan to medium-high heat. Cook chicken 6-7 minutes per side or until it is no longer pink and the internal temperature of 165 degrees F. Remove from heat and cool for at least 5 minutes. Slice or chop into small cubes.
While the chicken is cooking, combine the chopped tomato, jalapeno, onion, cilantro, and lime juice in a small bowl. Char tortillas on the stovetop over the flame until lightly charred (this step is optional).
Assemble tacos by placing about 1/4 cup of chicken into each tortilla. Top with a few tablespoons of the onion-tomato mixture and a drizzle of cilantro sauce (*optional, see recipe in notes).
To customize tacos, feel free to add sliced avocados or guacamole, chopped tomatoes, corn, shredded cheeseTo make cilantro sauce: combine 1/4 cup mayo or sour cream, 1/4 cup greek yogurt, 1 tablespoon lime juice, 2 tablespoons minced cilantro, and a pinch of salt and pepper. Stir to combine.