In a large dutch oven, or stock pot, heat the olive oil over medium heat. Add the beef and season with salt, pepper, Italian seasoning and red pepper flakes. Saute until the beef is lightly browned.
Add the onions, carrots and celery and saute about three minutes, just until the vegetables begins to soften.
Add the fire roasted tomatoes, tomato sauce and beef stock. Increase the heat to high and bring to a boil, reduce to simmer, cover loosely and simmer for one hour.
Bring the mixture back to a boil and add the alphabet pasta. Stir when adding the pasta so it doesn't clump.
Continue to boil, stirring often. Cook just the pasta is al dente (according to package directions).
Notes
Tips to cook Alphabet Soup Recipe
Stir the pasta while it's cooking.
That will ensure it doesn't stick to the bottom of the pan.
Additionally, stirring the pasta will release the starch and help thicken the soup.
This is a thick soup, add an additional cup of beef broth if you'd prefer a thinner soup.Cook just to al dente. As the soup cools the pasta will continue to cook and swell in size. Though you may think it's not enough pasta, you'll see it's the perfect amount!