Heat the olive oil in a large pot or Dutch oven over medium heat.
Add the diced onion and minced garlic, sautéing until the onion is translucent, about 3-4 minutes.
Increase the heat to medium-high and add the ground beef. Cook, breaking it apart with a wooden spoon, until browned and cooked through, about 5-7 minutes.
Drain any excess fat from the pot.
Stir in the diced tomatoes (with their juices), beef broth, orzo pasta, Italian seasoning, salt, and black pepper.
Bring the mixture to a boil, then reduce the heat to low, cover, and simmer for about 15-20 minutes or until the orzo is tender and has absorbed most of the liquid, stirring occasionally.
Once cooked, remove from heat and let it sit covered for a few minutes.
Fluff with a fork, then garnish with fresh chopped parsley before serving.