There was a study in the past couple days that showed nutrients in vegetables were better absorbed when the vegetable dressing contained oil (aka, the hated fat!).

Unfiltered, organic apple cider vinegar (or fresh lemon juice) + cold-pressed virgin olive oil ("vinaigrette" in French) is the perfect base for dozens variations of seasonings, like chives, oregano, parsely, garlic, onion, black pepper. It never gets boring and you know what's in it. Even some berry juice concentrate works well.