In a mixing bowl, combine plain flour and salt, then create a well in the center. Slowly stir in boiling water until the mixture becomes shaggy. Transfer to a floured surface and knead for about 10 minutes until smooth and elastic. Wrap in cling film and let rest for at least 30 minutes.

In a large bowl, mix together pork mince, chopped spring onions, chives, coriander, crushed garlic, chopped ginger, both soy sauces, sesame oil, rice wine vinegar, and egg. Season with salt and pepper. Let marinate.

Divide the dough into 8 pieces and roll each into a small ball. Flatten each ball into a thin circle about 4 inches wide. Place 1-2 tablespoons of the filling in the center. Fold over to create a half-moon shape, pinching edges to seal tightly.

Heat oil in a large skillet over medium-high heat. Place filled dumplings in the pan, smash each down gently, and fry for about 2 minutes until golden brown. Add water, cover, and steam for 1 minute, then remove lid and cook for another 2-3 minutes.

Remove from skillet and place on a serving platter. Top with shredded carrots, cucumber, spring onions, and coriander. Drizzle with chili oil and serve immediately.