Place red wine vinegar, Dijon mustard, garlic and salt in a glass or metal container with a tight fitting lid and shake to combine. Add olive oil and shake vigorously, until dressing emulsifies and thickens to the consistency of cream.
Let dressing sit for 1 hour at room temperature before straining out garlic and serving. Dressing can be refrigerated, but should be brought to room temperature and shaken again before serving.
Recipe courtesy of Alton Brown