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
¼ cup (or more) unseasoned rice vinegar
1½ teaspoons honey
Preheat oven to 425°. Toss bell pepper, chiles, garlic, shallots, and oil on a rimmed baking sheet to coat; season with salt. Turn garlic cut side down and roast until pepper and chiles are softened and blistered in spots, 10–15 minutes. Let cool.
Squeeze garlic cloves out of their skins into a food processor. Add bell pepper, chiles, shallots, vinegar, and honey and process until smooth. Taste chili sauce and season with more salt and vinegar if needed.
Do Ahead: Sauce can be made 5 days ahead. Cover and chill.