In a large pot, heat either butter or olive oil over medium heat. Once hot, add the chopped onions, carrots, and celery. Cook these fragrant vegetables for about 8-10 minutes until they soften and the onions become translucent.
Stir in the minced garlic along with the tomato paste and let it cook for about a minute.
Add in the diced potatoes and canned tomatoes (including their juices). Pour in 6–7 cups of vegetable broth along with Worcestershire sauce, brown sugar, Italian seasoning, seasoned salt, and celery salt. Bring everything to a nice boil.
Once boiling, toss in the dry orzo pasta. Lower the heat to a gentle simmer and let it cook for about 25-30 minutes.
With just five minutes left, stir in the frozen sweet corn. Taste your soup and adjust the seasoning with kosher salt and freshly ground black pepper.
Remove your pot from heat and stir in fresh parsley. Optionally, add a splash of lemon juice or apple cider vinegar.
Serve your Vegetable Orzo Soup warm in bowls garnished with freshly grated Parmesan cheese if desired.