Making your own dressing might be easier than you think. I add a variety of things including fresh ginger, jalapenos, cilantro or fresh herbs to change it up a bit.
1 or 2 cloves garlic, finely chopped
1-2 Tablespoons Dijon mustard
1/2 teaspoon salt
freshly ground pepper to taste (I like a lot of pepper)
1/4 cup vinegar
1 cup olive oil (I like a mixture of about half-and-half extra virgin and pure olive oil)
Put all ingredients except the olive oil in a blender or food processor. Turn on and pour in the olive oil.