Prepare all ingredients as listed above.
In a bowl, whisk together the garlic powder, oregano, lemon juice, and olive oil to create the marinade. Season with salt and pepper to taste. Add the chicken to marinate.
Preheat a grill or griddle pan over medium heat.
Grill the chicken on both sides to an internal temperature of 165°F (74°C). Set asdie.
Toast the buns on the grill.
Spread mayonnaise inside the bun. Layer with lettuce, tomato slices, grilled chicken, Swiss cheese, and red onion.
To make the sparkling chia fresca, combine all the ingredients together. Stir well and let sit for about 5 minutes to allow the chia seeds to bloom.
Serve the sandwiches alongside the carrot sticks, hummus, fresh blueberries, and chia fresca. .