In a large saucepan, heat the vegetable oil over medium-high heat. Add the onions, Italian seasoning, salt, and red pepper, and cook, stirring, until the onions are soft, 6 minutes. Add the garlic and fennel, and cook, stirring, for 2 minutes. Add the tomato paste and cook, stirring frequently, until paste begins to brown, about 5 minutes. Add the tomato sauce, pureed tomatoes, 2 1/2 cups of water, and Essence, and bring to a boil. Reduce the heat and simmer for 45 minutes, stirring occasionally.
In a large bowl, combine the ground chuck, sweet sausage, hot sausage, garlic, eggs, Essence, salt, and black pepper, and mix briefly but thoroughly to distribute seasonings. Shape into meatballs and set aside, refrigerated.
Add the meatballs to the sauce and do not stir until the meatballs float to the top of the sauce, about 10 to 12 minutes. Stir well, and simmer the meatballs in the sauce for 30 minutes, stirring occasionally and skimming any fat that rises to the surface. Taste, adjust seasoning as necessary, and serve immediately.