First, place the carrots and onion in the food processor and chop.
Coat the bottom of a large pot with 2 Tbsp of olive oil. Place carrot and onions in the pot and cook on medium to medium-low heat for 35 minutes. You want to caramelize the onions. Be careful not to burn them. If they begin to stick to the pan, add some water to deglaze the pot and continue cooking.
Meanwhile, season the short ribs liberally with salt and in a separate pan, brown the short ribs and sausage while the carrots and onions cook. Remove and set aside, but save the rendered fat. You'll add this to the carrots and onions later.
At the 35-minute mark of cooking the carrots and onions, they should have lost all their water and be a dark brown, but not burnt color. Add the minced garlic, fat-renderings, and tomato paste to the pot and stir for a few minutes. Be careful not to burn the garlic. Add red wine and cook until the liquid reduces (about 5 minutes).
Next, add the blended San Marzano tomatoes to the pot and mix.
Finally, season the pot with spaghetti seasoning, dried parsley flakes, basil, bay leaf, dried oregano, salt and pepper, and red pepper flakes (if using). Add the meats and mix all ingredients. Simmer on low heat for 6 hours or until the short ribs are fork-tender.