This lemon vinaigrette, from "Martha Stewart's Cooking School," works as a dressing for most salads.
Combine mustard, lemon zest, and juice in a jar; season with salt and pepper. Add some of the oil, then cover and shake to combine. Continue adding more oil and shaking until all the oil is incorporated and mixture is thickened and uniform in color. Serve immediately.
Martha used this vinaigrette recipe to make Poached Chicken Salad with Chopped Vegetables.