Heat a large pot over medium-high heat. Add the ground beef or sirloin and begin to break it up with a wooden spoon, cooking until brown and crisped. Add the diced onions and garlic and cook for about 5 minutes. Throw in the remaining veggies and continue to cook for another 5 minutes to soften. Add the canned tomatoes, tomato paste, beef stock and bring to a boil. Season with salt, pepper, cumin and paprika. Lower the heat and continue to cook for half an hour or until the potatoes are soft.