Easy Salad DressingsAll you need to make French dressing, put ketchup in the mayo or salad dressing and mix for the taste you like. Or use mayo or salad dressing, add mustard, and ketchup for Thousand Island dressing. For this one, you can put sweet pickle relish or any other herb or onions or hard boiled eggs, if you like. Sometimes, I just use plain salad dressing or mayo on the salad. I put it on just before serving the salad. You can also mix oil and vinegar, with herbs and garlic, if you want to make a nice Italian dressing.