Sweet Potato and Turkey Chili

Name: Sweet Potato and Turkey Chili
Ingredients: 3 teaspoons olive oil; 1 pound 99-percent fat-free ground turkey; 1 medium onion, diced; 3 cloves garlic, minced; 1/4 cup chili powder; 1 tablespoon ground cumin; 2 teaspoons ground coriander; 3 tablespoons tomato paste; Kosher salt and freshly ground black pepper; 2 medium sweet potatoes, peeled and cut into 1/2-inch cubes; 4 ripe plum tomatoes, chopped; Two 14-ounce cans black beans, drained and rinsed; 1/4 cup chia seeds; 1 to 2 tablespoons apple cider vinegar; 3 scallions, sliced; 1/4 cup reduced-fat sour cream, optional