To make the mustard sauce: Crack 1 egg into a small saucepan. With the heat on low, stir in mayonnaise, mustard and sugar. When it just starts to boil, it's done. Remove and let sit until cool, then chill for at least 10 minutes.
Place 6 whole eggs in a saucepan and cover with cold water. Bring water to a boil and cook eggs for 10 to 12 minutes. Remove from hot water, cool, peel.
Heat oil in deep-fryer to 375 degrees F (
Put the sausage into a bowl with the finely parsley, lemon rind, nutmeg, marjoram, salt and pepper. Work all the ingredients well into the sausage with your hands. Make a coating for each hand boiled egg out of the sausage, working it round the eggs with wet hands to form an even layer. Roll the covered eggs in beaten egg, and then in dried breadcrumbs.
Carefully slide in 3 eggs and fry for 4 to 5 minutes, until they turn deep golden brown. Turn them as they cook so that they brown evenly. Remove with a slotted spoon, drain on paper towel, and repeat with the remaining 3 eggs. Serve eggs with mustard sauce.