Peel back husks of corn and remove silk. Then cover corn with husk again. Next soak in large pot or bowl of water for at least 15 minuets. Remove corn from water and shake off excess water.
Peel back husk and rub corn with olive oil, then sprinkle each piece with a few dashes of garlic powder and onion powder. Recover corn with husk.
Place corn on a grill at medium heat. Turning corn frequently as husks char. Check a piece of corn by popping a kernel, if it pops easily and juice squirts it's done. At this point you can peel back husks and put back on grill for grill marks if desired, but be careful not to let corn dry out. Sprinkle with salt if desired.