2/3 cup extra-virgin olive oil
1/3 cup cider vinegar
1 big spoon of Dijon mustard
the juice of a lemon
coarse salt and lots of freshly ground black pepper
(1/2 teaspoon sugar, optional)

 
Combine all ingredients in a mason jar dug out of your fishing box.
Shake hard to mix.  Store in plastic tub, in walk-in cooler, for up to 1 week.  

 
Adjust belt one notch.