Toss a teaspoonful of salt in a deep pot with water, filled halfway through. Let it boil.
Using a spoon, gently drop the eggs into the boiling water. Leave to boil for only 8-10 minutes.
Prepare a bowl with ice water. Transfer the boiled eggs to this bowl to cool the eggs. Break off the shell with extra care.
Slice the eggs into a lengthwise motion to make two halves. Spoon out the yolks in each egg.
Transfer the removed yolks to a small bowl. Combine them with the mustard, sour cream, and mayonnaise. Season with the cayenne pepper and minced onion. Mix to combine entirely.
Stuff the halved egg whites with the produced yolk mixture. Use a piping bag (or pastry bag) or simply a teaspoon to do this.
Slice the olives in half, lengthwise. Get creative with the olives to make a spider. One half is the body while the other half should be the tiny legs.
Lay these spiders on the eggs and enjoy eating!