In a large bowl, whisk together first five ingredients. Slowly add olive oil while whisking constantly. Stir in pecans just before serving.
Test Kitchen tips
For the best results, start with all of the ingredients at room temperature. If the oil is cool or cold, it is much more difficult to form the emulsion.
To get the most flavor out of these simple ingredients, mix up the vinaigrette and let it sit at room temperature for 1 to 3 hours before serving. Refrigerate any leftovers; bring cold vinaigrette to room temperature before shaking to combine.
To toast nuts, bake in a shallow pan in a 350° oven for 5 to 10 minutes or cook in a skillet over low heat until lightly browned, stirring occasionally.