Cook the couscous according to package directions, drain, and place in a large bowl. While the couscous cooks, lightly toast the walnuts.
1 ½ cups pearl couscous
Heat a small skillet over low heat. Add the walnuts and cook for 5 to 7 minutes, tossing every couple of minutes until the walnuts begin to become fragrant. Remove from heat.
¼ cup walnuts
To the bowl of cooked couscous, add the cherry tomatoes, Kalamata olives, fresh parsley, feta cheese, toasted walnuts, and purple onions. Pour the vinaigrette over the ingredients and toss to combine.
½ cup cherry tomatoes, ½ cup Kalamata olives, ½ cup freshly chopped parsley, ½ cup feta cheese, ¼ cup purple onion, ½ cup lemon basil vinaigrette
Serve the salad warm or cold. Store any leftovers in the refrigerator for up to 3 days.