If using corn on the cob, lightly grease the cobs with oil and grill them on an outdoor or stove-top grill until corn is charred evenly all over.
Once slightly cooled, cut the kernels off the cob and add them to a bowl.
In a small skillet on medium-low heat, dry roast garlic and chili powder until fragrant, about 1~2 minutes. Add to the grilled corn.
If using fresh or frozen corn kernels, heat oil in a large non-stick skillet and add the fresh or frozen corn kernels. Cook on high heat, stirring occasionally, until corn starts on char. Add the garlic clove and chili powder and cook for 2 more minutes.
Remove the charred corn into a bowl and cool slightly.