1. Bring a large saucepan of water to the boil. Add eggs and simmer for 10 minutes for hard-boiled eggs. Drain and stand in cold water. Crack shells and gently peel. Trim the base of each egg so they stand up. Trim a third the top off each egg and scoop out the egg yolk.
2. Place the egg yolks, sour cream, mayonnaise, mustard, salt and pepper in a bowl and mash until smooth.
3. Spoon the egg yolk mixture into a piping bag or zip-lock bag. Snip the end off the bag and pipe the filling back into the eggs. Place on a serving platter and refrigerate.