Soak the mushrooms in a cup of warm water for about 10 minutes to reconstitute them. Squeeze out the water and finely chop the mushrooms. Strain the water to use in the ragù.
Heat the olive oil in a wide saucepan. Add the onion, garlic, parsley, carrot and celery. Sauté for about 10 minutes, mixing with a wooden spoon until softened and lightly golden.
Add the meat and the sausage meat and sauté on a medium heat until all the moisture from the meat has evaporated and the meat begins to brown. Add the red wine and cook until a lot of it has evaporated. Add the tomato passata and the paste, the mushrooms and the strained mushroom water. Season with salt and pepper. Cover and simmer for 2-2½ hours on a low heat. Add a little water when necessary to prevent the sauce from sticking and to maintain a good sauce consistency. Stir frequently to prevent the sauce from sticking.