Prep all the ingredients per the instructions above.
Mix the water and cucumber slices. Refrigerate until ready to serve.
Preheat a panini grill or skillet over medium heat. While heating, make the panini.
Spread the pesto onto one side of each slice of bread. Layer with mozzarella drizzled with olive oil, basil, and tomato seasoned with salt and pepper.
Grill the panini: Spray the panini grill with nonstick spray and heat. If using a panini grill, press the sandwich down, and cook until the bread is crispy and the cheese is melted. If using a skillet, cook both sides of the sandwich until golden brown and melted while covering with a lid.
To serve: Cut each panini in half and enjoy with carrot sticks with hummus and cucumber water.