In a shallow dish, combine the EVOO, cilantro, scallions, thyme, lime peel, half of the lime juice, and the hot sauce; season with salt and pepper. Add the chicken and let marinate for at least 30 minutes.
Preheat a grill or grill pan to medium-high. Grill the chicken until cooked through, 12 minutes. Just before the cooking time is up, top each breast with a slice of pepper jack cheese.
In a medium bowl, mash together the avocados, red onion, tomato, jalapenos, garlic, lemon juice and remaining lime juice; season with salt.
Top each bun bottom with lettuce, a chicken breast, a mound of guacamole and a bun top. Serve with the tortilla chips.