Preheat your oven to 375°.
Place the chickpeas on a baking sheet and bake in the oven for 10 minutes to dry them well.
Combine the sumac, the salt, the red pepper, and the olive oil in a medium bowl. Transfer the chickpeas to the bowl and toss.
Return the chickpeas to the baking sheet.
Bake at 375° for 55 minutes or until crisp and browned, stirring occasionally.
Transfer the chickpeas to a serving bowl and sprinkle with red wine vinegar. Serve immediately. Or if you're making these ahead of time, omit the vinegar and store the chickpeas in an airtight container.