Ingredients:

• 2 pounds sweet potatoes (3 medium or 2 large)
• 4 tablespoons olive oil, divided
• 1 tablespoon chili powder
• 3/4 teaspoon kosher salt, divided, plus more to taste
• 1/2 medium red onion
• 1 large lime
• 2 (14-ounce) cans black beans, drained and rinsed
• 1 to 2 packed cups baby spinach
• 1/4 teaspoon freshly ground black pepper, plus more to taste
• 4 ounces feta cheese, crumbled (about 1 cup)