1. Neatly slice the eggs in halves, and then scoop out the yolks.
2. In a mixing bowl, add the yolks, mayonnaise and mustard sauce and mix well. Add salt and pepper accordingly to your taste.
3. Take a piping bag fit with a nozzle, and fill in up with the egg mixture.
4. Carefully fill up the egg whites with the egg mixture, making neat swirls. Serve immediately.
Additions: You can top the eggs with chopped herbs such as parsley or coriander, or even oregano and chilli flakes.