Peel the lotus root, cut it in half lengthwise, and slice into 1cm thick pieces. Soak in water for 5 minutes, then pat dry with a paper towel. Cut the pumpkin in half horizontally and slice into 7mm thick pieces.

Cut the chicken thigh in half lengthwise and then into bite-sized pieces. Season with salt and pepper, then coat with potato starch.

In a shallow dish, combine all the Nanban Sauce ingredients (sugar, vinegar, soy sauce, water, and red chili) and mix until the sugar dissolves.

Heat vegetable oil in a frying pan to about 5mm depth over medium heat. Fry the lotus root and pumpkin until cooked through and golden brown, turning occasionally for 4–5 minutes. Transfer to the Nanban Sauce.