Boil a large pot of water. Add in the cheese tortellini. Boil for 1 1/2 minutes. Do not follow the package instructions.
Drain and immediately rinse with cold water.
In a large bowl add the tortellini, pesto, cherry tomatoes, mozzarella balls, red onion, kalamata olives, cucumber, salt, and pepper. Mix until fully incorporated.
Top with the basil.
Serve immediately or store in the fridge with a tight lid for up to 5 days.
Notes
Don't follow the package ingredients for cooking time, as the pasta will be too soft. Cook only until al dente.