Bring a pot of generously salted water to a rapid boil. Add the orzo and cook according to package directions, adding the corn in the last minute of cooking, until al dente, about 8 minutes. Drain and transfer to a medium bowl. Set aside.
Pour the lime juice over the avocado and coat evenly (this will minimize discoloration). Whisk together the olive oil, vinegar, sugar, cumin, and 1/2 teaspoon salt. Drizzle over the orzo and add the avocado with lime juice, tomatoes, and parsley. Mix until combined and serve warm or at room temperature.
Recipe courtesy of Mary Nolan