hot mustard dipping sauce
To make the hot mustard dipping sauce, combine the sour cream, mustard, lemon juice and salt in a bowl. Set aside. Heat the oil in a large, deep saucepan over medium heat until hot. Deep-fry the sweet potato, white sweet potato and yam, in batches, for 2–3 minutes or until golden and crisp. Drain on non-stick baking paper, sprinkle with the salt and serve immediately with the dipping sauce.