Carefully remove the kernels from the cobs. The best way to do this is to hold an ear by the tip and stand upright on the stem end in a bowl. Cut down the sides of the cob with a sharp knife, releasing the kernels without cutting into the cob.
Heat the oil in the skillet over medium heat until smoking. Add the kernels and cook, stirring, until nicely crisp, about 10 minutes. Season with salt and set aside to cool.
When ready to serve, combine the corn, red pepper, onion, cilantro, scallion, vinegar, and sugar. Mix well and season with salt and pepper. Serve immediately.