Pour red wine vinegar into a small bowl.
Add the salt and fresh-ground black pepper.
Stir to dissolve the salt, taste, and adjust if needed.
Use a fork or small whisk to beat in the extra-virgin olive oil, a little at a time.
Taste as you go and stop when it tastes right.
For variations:Add a little puréed garlic or diced shallot, or both, to the vinegar.
White wine vinegar, sherry vinegar or lemon juice can replace some or all of the red wine vinegar.
Beat in a little mustard before you start adding the oil.
For part of the olive oil, substitute a very fresh nut oil, such as walnut or hazelnut.
Heavy cream or crème fraîche can replace some or all the olive oil.
Chop some fresh herbs and stir them into the finished vinaigrette.