Of course you can always make deviled eggs with your hardboiled eggs. But there are so many versions within that standard idea. Provençal flavors of basil pesto (called pistou in France) and ratatouille are the star of this version. You can either make your own pesto, which we hope you are using for another recipe as well, or simply buy a jar of ready-made pesto. It goes really well with the mayonnaise, fresh lemon juice, Dijon mustard, and chopped fresh basil. This recipe assumes you have some fresh ratatouille laying around, waiting to garnish your latest creations. It's optional. If you did have something with garlicky tomatoes, zucchini, and eggplant, that would be an awesome topper. Just saying.