You can actually make some really good burger sauce by using mayonnaise as a base. Recipe:
Two eggs
1/2 tsp salt
1/2 tsp ground white peppercorns
1tsp strong English mustard
1tsp Dijon mustard
1 tsp habanero sauce
1 tsp runny honey
3 cloves garlic, peeled
half a small white onion, peeled
1 tsp dried oregano
1tsp cumin
1/2 tsp turmeric
Good quality vegetable oil
Put the mustards, eggs, salt, pepper, habanero sauce, runny honey, cumin and turmeric into a blender and whizz for a few seconds, then put on the lid, open the pouring hole in the blender and turn it on, adding vegetable oil in a very slow, steady, consistent stream until the mix thickens and becomes the consistency of mayonnaise.
Remove the mayonnaise from the blender into a bowl, then put the garlic, onion and oregano into the blender and blitz until puree. Put the onion/garlic mix into the bowl and mix it all together.
Simples.