Prep the ingredients per the instructions above.
In a bowl, whisk together the garlic powder, dried oregano, lemon juice, and olive oil to make the marinade. Season with salt and pepper to taste. Adjust until the marinade tastes well balanced.
Place the chicken in the marinade to coat well.
Preheat a grill or griddle pan over medium heat.
Grill the chicken on both sides to an internal temperature of 165°F (74°C). Remove and let rest for 5 minutes.
Lightly grill or toast the buns until golden brown, then set aside.
Assemble the sandwich by spreading mayonnaise on the inside of each bun. Layer with butter lettuce, tomato, grilled chicken, Swiss cheese, and red onion.
To make the chia fresca, combine all ingredients together. Let sit 5 minutes for the chia to bloom.
Serve the grilled chicken sandwich with carrot sticks and hummus, blueberries, and sparkling fresca.