If you add the oils too quickly, your dressing won’t emulsify properly and will “break” - and the dressing will be runny. To avoid throwing it out, try this method from www.seriouseats.com to fix it (visit the full article here): 1. Place a teaspoon of water or lemon juice in a small bowl. 2. Slowly whisk in some of the broken dressing until it starts to emulsify (thicken). 3. Slowly whisk in the rest of the broken dressing.