Brush olive oil on the peppers, and place them cut side down on a piece of heavy duty aluminum foil (with the edges turned up to avoid drips.) Roast until charred, them remove them to a resealable plastic bag or tightly covered pan to sweat and cool down.
Make the vinaigrette just before use. Through the feed opening of a running blender, add vinegar and garlic. With the blender still running, pour olive oil in a slow thin stream. (Alternatively, you can prepare the vinaigrette by whisking the ingredients into a bowl in the same order, in which case, the garlic should be minced first.)
Return to the bell peppers and peel off the blackened skin. Slice the flesh of the peppers brunoise (julienne, then crosswise) and place in a mixing bowl. Fold in the drained black-eyed peas, scallions, and parsley. Stir in enough of the vinaigrette to coat. Serve family style.