Whisk pesto, vinegar, oil, salt and pepper in a bowl, then reserve 4 tbs. of pesto and set both bowls aside.
Add arugula and quinoa to the large bowl with the vinaigrette and toss to coat.
Divide the arugula mixture between 4 bowls.
Top with tomatoes, avocado and shrimp.
Drizzle each bowl with 1 tablespoon of the reserved pesto mixture.