Step 1: Cook the Tortellini. Bring a large pot of salted water to a rolling boil. Add the tortellini and cook according to package directions until al dente (usually 3-5 minutes for fresh tortellini). Do not overcook.
Step 2: Drain and Rinse. Once cooked, drain the tortellini thoroughly in a colander. Rinse with cold water to stop the cooking process and prevent sticking. Set aside to cool completely.
Step 3: Prepare Ingredients. While the tortellini cools, halve the cherry tomatoes. Drain the fresh mozzarella balls. If using a block of mozzarella, cut it into bite-sized cubes. Chop fresh basil for garnish.
Step 4: Assemble the Salad. In a large mixing bowl, combine the cooled tortellini, halved cherry tomatoes, and fresh mozzarella balls.
Step 5: Add Pesto. Pour the basil pesto over the tortellini mixture. If the pesto is very thick, you can add 1-2 tablespoons of extra virgin olive oil to help it coat the ingredients more easily.
Step 6: Gently Toss. Gently toss all the ingredients together until everything is well combined and evenly coated with the pesto. Be careful not to mash the tortellini.
Step 7: Season and Chill. Season the tortellini pasta salad with salt and freshly ground black pepper to taste. Cover the bowl and refrigerate for at least 30 minutes, or preferably 2-4 hours, to allow the flavors to meld and the salad to chill thoroughly.
Step 8: Garnish and Serve. Before serving, give the salad another gentle toss. Garnish with fresh chopped basil leaves for a burst of color and fresh aroma. Enjoy your ultimate pesto tortellini pasta salad!