Optional: Toast the whole grain bread until lightly golden, then allow it to cool slightly.
Spread Dijon mustard evenly over one side of each slice of bread.
Layer with arugula, ham, and Brie cheese.
Close the sandwiches with the remaining bread slices, mustard side down, and cut in half.
Combine the sparkling water, orange slices, and chia seeds. Stir thoroughly, let sit for 2–3 minutes.
Serve the sandwich with carrots, hummus, pickle spears, and orange chia sparkling water.