To make your own oil and vinegar dressing, also called a vinaigrette you'll need 3/4 cup vegetable oil (or oil you prefer) 1/4 cup white wine vinegar, salt and pepper. Add all ingredients in a blend and blend until fully mixed, about 10 seconds. Move to a glass dish and let stand 30 minutes, whisk before serving.
A simple oil and vinegar dressing is known as vinaigrette and is a temporary emulsion as oil and vinegar do not mix. To make a good vinaigrette you need oil and vinegar in the ratio of 3:1. You can then either whisk, blend or shake it to form the emulsion and season with salt and pepper.