Heat the oil a large saucepan or high-sided skillet over medium-high heat. Add the beef and cook until browned on all sides. Add the onion and cook for 3 to 5 minutes, until tender.
Add the tomatoes and garlic and cook for 1 minute. Add the coriander, cumin, 1/2 teaspoon salt, and 1/4 teaspoon black pepper and stir to coat. Cook for 30 seconds, until fragrant.
Add the broth (or water) and bay leaves and bring to a boil.
Reduce the heat to medium, cover, and simmer for 45 minutes.
Add the potatoes, carrots, and bell pepper, increase the heat to high and bring to a boil. Reduce the heat to medium, cover, and simmer for 30 minutes, until the beef and vegetables are tender.
Meanwhile, cook the pasta according to the package instructions. Drain, rinse under cold water to prevent further cooking, and set aside (cover to prevent noodles from drying out).
Remove the bay leaves. Season to taste with salt and pepper.
Add the pasta to the pot with the beef and cook for 1 to 2 minutes to heat through. Alternatively, you can serve the meat and vegetables over the hot noodles and add less of the broth.
Garnish with green onions and serve.