Using a food processor, finely chop 1 quartered green bell pepper, 2 quartered mild chiles, and 1 halved jalapeno chile. Scrape down the sides of the bowl. Add 1/4 cup flat-leaf parsley leaves, 2 cloves garlic and 3 tablespoons chopped pepperoncini and pulse a few more times. Add 3 tablespoons red wine vinegar, season with salt and continue processing until the mixture is a coarse puree, about 5 seconds. Strain before serving at room temperature.