Cook the pasta per package instructions. Drain but do not rinse.
Meanwhile, roast the corn. Brush lightly with oil and place on a hot grill or under a broiler, rotating often until lightly browned and cooked.
Let the corn cool slightly before cutting the kernels off the ears. Transfer to a large bowl.
Add the beans, olives, tomatoes, green onion, red onion and cheese, if using. Toss gently to mix.
Add the dressing and cooking pasta and stir gently to coat.
Refrigerate at least 2 hours before serving. Garnish with additional green onions if desired. Note: If the salad is too thick, stir in some more salsa or mayonnaise before serving.