In a medium jar or bowl, combine olive oil, balsamic vinegar, minced garlic, and Dijon mustard. Season with salt and pepper. Whisk until emulsified.

Bring a large pot of salted water to a boil. Add orzo and cook for 7-9 minutes until al dente. Drain and cool for 10 minutes.

Chop sun-dried tomatoes and soak in hot water for 5 minutes. Drain well.

In a large bowl, combine cooled orzo, sun-dried tomatoes, and baby spinach. Gently fold together.

Drizzle vinaigrette over the salad and toss gently to coat. Adjust seasoning as needed.