In a mason jar or a small bowl, combine the olive oil, white vinegar, water, Italian dressing mix, sugar (or honey), and mayonnaise.
Add a pinch of salt and ground black pepper to taste.
Shake the jar vigorously or whisk the ingredients together until well combined.
Serve the dressing over your favorite tossed salad.
Store any leftover dressing in the refrigerator for up to 2 weeks. Make sure to shake well before serving.