1. Add the olive oil and onion to a medium skillet over medium heat. Cook until the onion is translucent and soft, about 8 minutes. Remove from the heat and let the onion cool.
Cook the orzo according to the package directions.
2. Grill or boil the corn until cooked and tender, about 5 minutes. Cut the kernels from the cobs.
3. Mix together the onions, orzo, cherry tomatoes and corn in a large bowl. Gently fold in the rocket. Drizzle with lemon oil and sprinkle the Parmesan on top.