A whole range of flavor possibilities can be achieved by varying the herbs in this recipe, and adding the yogurt both frees up the consistency and gives a welcome tartness.
1 egg yolk
1 cup packed fresh green herbs (basil, oregano, garlic, chives, parsley, and tarragon, or whatever is available)
1 tablespoon wine vinegar
1 teaspoon Dijon mustard
2/3 cup corn oil, more or less
1/2 cup yogurt (optional)
Pepper to taste
Place egg yolk, herbs, vinegar, mustard, and 2 tablespoons of the oil in a food processor or blender. Mix until smooth. Slowly dribble in more oil as needed to make a smooth mayonnaise. To make the consistency of salad dressing, add yogurt, season with pepper, and mix well.