Lettuce, Arugula, and Mint Salad

2 1/2 tablespoons Sherry vinegar or white-wine vinegar
2 teaspoons Dijon mustard
1/3 cup olive oil
about 10 cups salad greens
1 large bunch arugula, coarse stems discarded and the leaves rinsed and spun dry
1 bunch worth of mint leaves, rinsed and spun dry

In a bowl whisk together the vinegar, the mustard, and salt and pepper to taste, add the oil in a stream, whisking, and whisk the dressing until it is emulsified. In a large bowl toss the greens with the dressing.

Serves 6-8.