Sweet and Spicy Sweet Potato Soup
1 lime, cut into wedges 1 lime, zested and juiced 1 pound tart apples, cored and cut into 1/4-i… 2 (15 ounce) cans sweet potatoes, drained 2 quarts chicken broth 2 tablespoons grated fresh ginger 3 tablespoons olive oil 4 shallots, sliced ¼ teaspoon ground cayenne pepper, or more to … ¼ teaspoon red pepper flakes, or more to tast… ½ teaspoon salt, or to taste