Add enough oil to a large stockpot to thinly coat the bottom; heat over medium. Add 1 onion, carrots, garlic, bay leaf, red pepper flakes, Greek seasoning, rosemary, thyme, basil, Italian seasoning, salt, and black pepper; cook and stir until mixture begins to soften and brown.

Add tomatoes and ground beef, breaking beef apart with a wooden spoon; bring to a boil. Cook until beef is cooked through and carrots are tender.

Add potatoes, remaining onion, and celery; cook until potatoes are tender.