1. Slice eggs in half, lengthwise and remove yolks into a bowl. Set egg white halves aside.
2. Pass egg yolks through a fine sieve into a bowl.
3. Add to the yolks the finely chopped red onion, ¼ tsp of salt, paprika, mustard and mayonnaise.
4. Using a spatula or wooden spoon, combine all the ingredients to achieve a smooth and even consistency.
5. Fill yolk mixture into a piping bag or into a zip lock baggie with the corner cut to a small hole.
6. Pipe yolk mixture into the empty yolk cavity in the egg white halves.
7. Garnish by sprinkling paprika on top.