Add the oil to a large skillet and place it over medium-high heat for 2 minutes. Add the onions. Cook 5 minutes, stirring occasionally.
Add the ground beef (or ground lamb) to the skillet and break it apart with a wooden spoon. Add the parsley, rosemary, thyme, salt, and and pepper. Stir well. Cook for 6-8 minutes, until the meat is browned, stirring occasionally.
Add the Worcestershire sauce and garlic. Stir to combine. Cook for 1 minute.
Add the flour and tomato paste. Stir until well incorporated and no clumps of tomato paste remain.
Add the broth, frozen peas and carrots, and frozen corn. Bring the liquid to a boil then reduce to simmer. Simmer for 5 minutes, stirring occasionally.
Set the meat mixture aside. Preheat oven to 400 degrees F.