2 tablespoons vegetable oil
1 tablespoon white wine vinegar
1 tablespoon olive oil
½ teaspoon Dijon mustard
salt and pepper

Put all the ingredients into a screw-top jar and shake vigorously until blended well.
Variations: add finely snipped herbs such as tarragon or chives, or even finely sliced shallots.
Use different vinegars or lemon juice. This dressing keeps
perfectly in the refrigerator for several days.