Add the oil to a large pot and heat over medium heat. Add the ground beef and using a spatula or potato masher, break up the beef to cook evenly. Add ½ a cup of water and break apart again. Cook for a few minutes until the beef has browned.
Add the onions and peppers, stir into the meat. Cook until the onions are translucent. (Lower the heat if the beef starts to burn and add a few tablespoons of water if needed)
Once the onions have cooked, add the sofrito, garlic, oregano and sazon. Stir well to combine into the meat.
Add the tomato sauce, salt and pepper to taste and stir. Lower the heat if needed to medium low. Cook for 20-25 minutes semi-covered with a lid.
While the sauce is cooking, cook the spaghetti per the box instructions.
Once the sauce is done, taste for salt and pepper and add more if needed.
Add the meat sauce a little at a time to the spaghetti and incorporate well. Continue adding more of the sauce until the spaghetti is combined well with the sauce.
Once enough of the meat sauce has been added to the spaghetti, you can reserve the rest for serving on top of individual servings. Or you simply add all of the sauce now to the pasta if you prefer.