Makes about 1 1/2 cups INGREDIENTS • 1 red bell pepper, halved lengthwise, seeds and ribs removed • 2 Fresno chiles, seeds removed if desired • 1 head of garlic, halved crosswise • 2 small shallots, peeled • 2 tablespoons vegetable oil • Kosher salt • ¼ cup (or more) unseasoned rice vinegar