Here’s a trick you can use with pesto but also with other condiments such as harissa that you may have in your fridge.
✨Add vinegar - I like to use red wine vinegar - and voila, you have salad dressing! You can also add lemon juice, white wine vinegar or apple cider vinegar. Something to provide that acidic bite which screams VINAIGRETTE.
How much? It depends. I would start with a 3:1 ratio - for every 3 tablespoons of pesto, add one tablespoon of red wine vinegar. Whisk to mix, do a taste check and add more if needed, 1/2 tbsp at a time. I usually do this in a small glass jar with a tight screw on lid so I can shake the jar to mix it in instead of using a tiny whisk. It should taste a little uncomfortably acidic for it to work as a salad dressing.
You can also add a dash of Dijon mustard (and whisk or shake!) to bind the emulsion of oil and vinegar and avoid it separating into layers.
I love doing this for pasta salads or grain salads to add some freshness, especially when I meal-prep to store them chilled. But you could also use it to dress greens. Or potatoes. Try it and let me know what you think!