Clean the mushrooms with a damp towel, cut them in half and then into slices.
Heat the olive oil in a pan, over medium to high heat, and sauté the onions with the rosemary for 2 minutes. Add the mushrooms and continue sautéing for 5 minutes. Add the garlic and continue for another 2 minutes.
Then, deglaze with the soy sauce, stir and then add the almond milk, nutmeg, salt and pepper. Lower the temperature and simmer for 5 minutes.
Dissolve the corn flour in half a cup of warm almond milk from the pan. Then put it back together with the mushrooms and simmer for 5 minutes or until the soup slightly starts to thicken.
Serve it warm as a first or a main course. You can garnish with chopped parsley, freshly ground pepper or croutons. It is accompanied wonderfully with white wine.
Notes
To make the mushroom soup more presentable, you may use very small slices of mushrooms. If the mushrooms are large, cut them first into quarters and then into slices.
Instead of a pan, you can use a wok or a non-stick pot.