Preheat an outdoor charcoal grill to medium-high. Rub the peppers with oil and season them with salt and pepper. Place the peppers directly on the grill and roast for 10 minutes, turning periodically with tongs, so they are really charred and blistered on all sides. Put the peppers into a bowl, cover with plastic wrap, and steam for about 10 minutes to loosen the skins. Pull out the cores of the red peppers and remove the seeds. Peel the blackened skins and tear the peppers into strips; put them on a serving platter.
Put the onion, tomatoes, garlic, and parsley on a cutting board; chop everything up into bite-size pieces and swipe the mixture into a bowl; season generously with salt and pepper. Pour in the vinegar and oil, mix well to incorporate the ingredients. Taste and adjust seasonings as needed. Pour the salsa over the roasted red peppers and serve at room temperature with beef or other dishes.