In your largest pan with straight sides and a lid, add the olive oil on medium-high heat. When the oil begins to swirl, add the bell pepper, onions, Italian seasoning, a pinch of salt and a few grinds of pepper. Cook until the vegetables are tender and the onions become translucent, about 8 minutes. Add the garlic and stir.
Add the sausage and beef in parts around the pan. Cook while breaking up with a wooden spoon until both are cooked through and browned, 10 to 12 minutes. Add the tomatoes and stir. Add enough stock to cover the contents by almost an inch. Bring the pan to a boil then add the broken lasagna sheets. Nudge and nestle them beneath the level of liquid. Cover the pot, lower the heat to a simmer and cook until the lasagna noodles are al dente, 6 to 8 minutes.
In a medium bowl, mix the ricotta and the lemon zest. Evenly scoop the pan-sagna into shallow serving bowls. Immediately top each with some shredded cheese, a dollop of the ricotta blend, and garnish with some basil and parsley.