Heat a grill to medium. Brush the corn with canola oil and season with salt and pepper. Grill until lightly charred on all sides, 2 to 3 minutes per side. Set aside to cool slightly, then slice the kernels off the cobs and reserve.
Heat the 2 tablespoons canola oil in a large skillet over medium heat. Add the red onions, bell peppers and Fresno chile; cook, stirring occasionally, until soft, about 5 minutes. Add the garlic and cook 30 seconds. Add the black-eyed peas and cook another 2 minutes. Add the sugar and vinegar; bring to a boil; and cook, stirring occasionally, until the sugar dissolves, about 3 minutes. Fold in the reserved corn and the parsley and transfer to a serving bowl. Serve warm or at room temperature.