Warm Black Bean Dip

INGREDIENTS

• 2 tablespoons olive oil
• 1 teaspoon kosher salt
• 1 large yellow onion, finely diced
• 3 garlic cloves, minced
• 1 tablespoon chili powder
• 2 (15½-ounce) cans black beans, drained and rinsed well, divided
• 2 canned chipotle chiles, minced + 3 tablespoons adobo sauce (from a can of chipotles in adobo sauce)
• ¾ cup water
• 3 tablespoons apple cider vinegar
• 1 (14.5-ounce) can diced tomatoes, drained and chopped
• 1½ cups frozen corn, thawed
• 6 ounces sharp Cheddar cheese, shredded (about 1½ cups), divided
• 6 ounces sharp Monterey Jack cheese, shredded (about 1½ cups), divided
• ¾ cup chopped cilantro, divided
• Freshly ground black pepper