If there is one thing every person should know how to do it the kitchen, I'd say it should be knowing how to make your own salad dressing.
That stuff that comes in the bottle has all kinds of stuff in there that you don't need, it doesn't taste as good, and it is overly expensive.
In the summer when avocados are readily available, make use of them for this yummy and creamy dressing:
-1 large ripe avocado, peeled and pitted
-3 T fresh herbs (choose from parsley, basil, thyme, tarragon, lemon verbena)
-2 1/2 T fresh lemon juice
-1/2 cup olive oil
-1/2 t salt
-1/2 cup purified water
If you want to thicken it a bit, add a tablespoon or so of tahini.