To make a bouquet garni, tie the sprigs of thyme, rosemary and sage together with kitchen string. (This will make it easier to pull the herbs out of the sauce before serving.)
Combine the porcini mushrooms and measured boiling water in a bowl. Set aside to rehydrate.
Heat the oil in a saucepan over medium heat. Add the onion and carrots and sweat for 7 minutes, until softened and translucent. Chuck in the vegan lardons, garlic and whole mushrooms and cook for another 7 minutes.
Drain the porcini mushrooms, reserving the porcini soaking liquid for later. (The water is full of umami flavour and will help add depth to your sauce.) Squeeze out all the excess water from the porcini, then finely chop them.
Add the porcini and tomato purée to the pan and stir. Cook for 5 minutes, then add the butter beans and bouquet garni. Pour in the soaking liquid, taking care to leave out any bits of grit at the bottom. You definitely do not want that in your stock. Pour in the wine and stock.
Mix the cornflour with the measured water to make a loose paste, then add it to the sauce. Season with salt and pepper. Bring the sauce to a boil, then reduce the heat to medium- low. Simmer for 30 minutes, until sauce has thickened.
Discard the bouquet garni from the bourguignon.
