Special equipment: an immersion blender
For the tomato sauce: Combine the whole tomatoes and liquid from the can, onion, 2 cloves of the garlic, basil, oregano, olive oil, salt and black pepper in a 2-gallon container and puree with an immersion blender until smooth.
Heat a large saute pan over high heat until it begins to smoke. Reduce the heat to medium and add the grapeseed oil and remaining 2 cloves of garlic and quickly saute. Add the diced tomatoes and saute until heated through, 1 to 2 minutes. Add the pureed tomato sauce and bring to a simmer. Cook for 15 minutes and remove from the heat.
For the stuffed peppers: Preheat the oven to 350 degrees F. Bring 1 gallon water and 2 tablespoons salt to a boil in a 2-gallon pot. Add the pasta and stir continually for the first 2 minutes of cooking to make sure it doesn't stick, then stir occasionally until the pasta is cooked to al dente, about 9 minutes.
Strain the pasta, spread it on a cookie sheet and drizzle with the olive oil. Mix to coat and refrigerate until cold.
Heat a saute pan over medium heat and add the grapeseed oil and sausage. Cook the sausage, stirring with a wooden spoon to break up the chunks, until browned and fully cooked, about 15 minutes. Remove from the pan, spread on a cookie sheet and refrigerate until cold.
Preheat the oven to 350 degrees F. Combine the orzo and sausage in a mixing bowl with the diced tomatoes, Parmesan and basil. Season with salt and black pepper.
Cut the top off each bell pepper and remove the seeds and ribs from the inside. Trim the bottom of each pepper so it will sit upright on the plate.
Stuff the peppers with the sausage mixture and top with the mozzarella. Arrange in a 9-by-13-inch baking dish, cover with foil and bake for 20 minutes. Remove the foil, return the peppers to the oven and bake until tender, 5 to 10 minutes more. Remove from the oven and allow the peppers to sit for 5 minutes.
For the broccoli rabe: Combine 2 gallons of water and 4 tablespoons salt in a large pot and bring to a boil. Prepare an ice bath for shocking the broccoli rabe.
Add half of the broccoli rabe to the water and cook until al dente, 3 to 4 minutes. Strain the broccoli rabe from the water and shock in the ice bath. Bring the water to back up to a boil and repeat with the rest of the broccoli rabe.
Remove the broccoli rabe from the ice bath and pat dry with a towel.
For plating: Reheat the tomato sauce to a simmer over medium heat.
Heat a saute pan over high heat until it begins to smoke. Add the grapeseed oil and then add the blanched broccoli rabe. Saute for 2 to 3 minutes and then season with the black pepper and 2 teaspoons of the salt.
Pool about 4 ounces of the tomato sauce on 6 plates. Divide the broccoli rabe among the plates, putting it in the center of the plate and making the pile flat so you can place the stuffed pepper on top. Place the stuffed pepper on top of the broccoli rabe and serve immediately.