Cut the chives into 4cm pieces.

Place the frozen udon noodles on a microwave-safe plate, cover loosely with plastic wrap, and heat according to package instructions.

Heat salad oil in a frying pan over medium heat. Add the peeled shrimp and stir-fry until they change color. Add the beaten egg and stir-fry until semi-cooked, then remove from the pan.

Add bean sprouts and chives to the pan and stir-fry briefly. Add the heated udon noodles and stir-fry while loosening them. Mix in the seasoning ingredients (sugar, fish sauce, lemon juice, chili paste), then return the shrimp and egg to the pan and stir-fry together.