Not a real recipe, but I like this some times because it is so simple. I usually use this when there is seafood in a salad such as fresh spinach and shrimp.
Olive oil, just enough to lightly cover the spinach, don't saturate the spinch.
Fresh lemon juice. I slice lemon in half, pick out the seeds and sqeeze over spinach, taste to see if enough and add more if necessary. A light touch of lemon juice is better for me.
Add salt and pepper to taste.