I never thought that I could make a salad dressing that would taste as good as bottled. For too many years I bought bottled. I can't afford it now, so I had to confront my dressing-impairment directly.
Sat down with Bittman's How to Cook Everything and read his diatribe re bottled dressings. The key to making better dressings, he explained, was a blender, which would thoroughly emulsify the oil and vinegar. Oy, what a dumbkopf I've been, with my puny fork-whipped dressings. No wonder they separated immediately.
I blended some fancy organic olive oil, balsamic vinegar, lemon juice, and a large garlic clove. Success! I am enjoying wilted-cabbage-and-peanut salad right now :)