1. In a small bowl, whisk together vinegar, mustard, salt, and pepper.
2. Drizzle in olive oil, whisking constantly.
3. Stir in oregano. Cover and set aside.
4. Bring large pot of water to a boil over high heat.
5. Add snap peas and simmer 4 minutes, until crisp-tender.
6. Drain and rinse under cold water.
7. Place snap peas in a large bowl.
8. Add tomatoes, bocconcini, carrots, olives, and red onions, toss.