1) Remove the husks of the corn but leave the core attached at the end so you have something to hold onto. Griddle the corn on a hot griddle or cast iron griddle pan until slightly charred. Turn it so it gets cooked evenly all over.
2) Mix the mayonnaise, soured cream and coriander together. Grate the Parmesan in another bowl.
3) While the corn is still warm slather with mayonnaise mix. Squeeze lime juice over the corn and shower with Parmesan.
4) Season with chili powder and serve with extra lime wedges.