In a large skillet, heat the oil over medium-low heat. Add the bacon and cook until crisp, about 5 minutes. Using a slotted spoon, transfer the bacon to a paper towel to drain. Measure the fat remaining in the skillet--you need 2 tablespoons. (If the bacon was particularly lean and you don't have enough, add olive oil to make up the difference.)
Add the potatoes to the skillet and cook, tossing occasionally, until golden brown, about 5 minutes. Add the bell peppers and some salt and cook, tossing occasionally, until the peppers and potatoes are tender, about 5 minutes longer.
Add the corn and cook until piping hot, 3 to 5 minutes. Transfer to a bowl. Add the vinegar and onions, season with salt and red pepper flakes and stir to combine. Serve warm, at room temperature or chilled.