Soak the porcini in 300ml of boiling water for 20 minutes or longer.
Heat the 1 tablespoon of olive oil in a large non-stick frying pan and fry the onion until soft, about 5 minutes.
Cook the mushrooms in two batches using the remaining 4T of olive oil, and when done, add them all back to the pan.
Add the garlic and herbs and stir.
Add the wine and allow the liquid to slowly cook off.
Drain the soaked mushrooms (reserving the liquid), squeeze the liquid out and roughly chop, adding them to the mushroom mix.
Pour the mushroom liquid / stock into the pan and let it simmer until most of the liquid is cooked off, or to your level of liking. Stir in the miso paste or soy sauce.
Add the cream if you are adding it and allow to cook for a further 2 - 3 minutes.
Check the seasoning and adjust where necessary. I find a god few grinds of black pepper are nice.
While the mushrooms are cooking, make your toasts in the oven or these can be made in advance.
Serve the mushrooms warm on the toasted.