Cut corn from cobs, if using. In a large saucepan bring about 1/2 inch water to boiling. Place a steamer insert in the saucepan so bottom doesn't touch the water. Add corn to steamer insert. Cover and steam for 2 to 4 minutes or until corn is crisp-tender.
In a large bowl combine corn, queso fresco, sweet pepper, red onion, and, if desired, chile pepper.
For dressing, in a screw-top jar combine olive oil, lime juice, cilantro, salt, and black pepper. Cover and shake well to combine.
Add dressing to corn mixture; toss gently to combine. Chill for 2 hours before serving.