The potatoes should be cooked for about 10 minutes in a pot of salted boiling water. Drain, then leave to cool.
The cooked potatoes, cherry tomatoes, red onion, mozzarella cheese, and basil should all be combined in a big bowl.
Mix the olive oil, red wine vinegar, Dijon mustard, salt, and pepper in a small bowl.
The potato mixture should be poured the dressing over it, then gently mixed.
For at least 30 minutes or up to 2 hours, cover the salad and place it in the refrigerator.
Serve chilled.