Prep all ingredients according to the descriptions above.
In a bowl, mix all the ingredients for the marinade. Set aside.
Preheat a grill or griddle pan over medium heat.
Grill the chicken on both sides to an internal temperature of 165°F (74°C). Use a thermometer to confirm doneness.
Remove the chicken from the heat and let it rest for 5 minutes.
Lightly grill or toast the buns until golden brown. Set aside.
Assemble the sandwiches: Spread mayonnaise on the inside of both halves of each bun. Layer the bottom half with lettuce, tomato slices, grilled chicken, Swiss cheese, and red onion. Top with the other half of the bun.
For the chia fresca, stir together all the ingredients until combined. Let it sit for 5 minutes to allow the chia seeds to expand. Stir again.
Serve the sandwiches with carrot sticks and hummus, fresh blueberries, and chia fresca. Enjoy!