2 tablespoons olive oil
1 medium yellow onion, diced
2 medium celery stalks, diced
2 cloves garlic, minced
2 pounds sweet potatoes (2 to 3 medium potatoes), peeled and diced
1 teaspoon ground coriander
1 teaspoon sweet paprika
1/2 teaspoon dried sage
1 teaspoon kosher salt
1/4 teaspoon freshly ground black pepper
4 cups vegetable stock