1) In a small bowl, whisk together the vinegar, mustard, garlic, egg yolk, salt, and pepper. While whisking, slowly add the olive oil until the vinaigrette is emulsified.
2) Toss the greens with enough dressing to moisten and serve.
*Note: If you're worried about raw egg, eliminate it from the recipe. Food Network Kitchens suggest caution in consuming raw and lightly-cooked eggs due to the slight risk of Salmonella or other food-borne illness. To reduce this risk, we recommend you use only fresh, properly-refrigerated, clean, grade A or AA eggs with intact shells, and avoid contact between the yolks or whites and the shell.