Clean the mushrooms and cut them in half.
Heat the oil in a skillet and sweat the mushrooms for 5 to 7 minutes with a pinch of salt, to draw out their water and flavor.
Add enough water to cover and bring to a bare simmer for 20 minutes.
Strain through a fine-mesh sieve and set the mushrooms aside for the filling.
Measure out 250 ml (1 cup) of the broth and pour it into a saucepan with the orange juice, carrot juice, sliced ginger, and rice vinegar. Simmer gently over low heat for 8 to 10 minutes to concentrate the flavors. Taste as you go and, if needed, keep reducing for more concentration.
Strain into a container, add the oil, and blend with an hand blender.
Roughly chop the parsley.
Take the mushrooms used for the broth and blend them with the parsley, olive oil, and miso. Season to taste with salt and pepper.
Peel the carrots and trim the ends, keeping 10 cm (4 in) of the widest part.
Using a mandoline, cut them into ribbons of 2mm.
Blanch the ribbons in a saucepan of salted water for 2 minutes, then transfer them immediately to a bowl of ice water to lock in the color and stop the cooking.
Pat dry on a kitchen towel.
Lay 2 ribbons in a cross, place a teaspoon of filling in the center, then fold in each corner to form a wrap.
Steam the dumplings for 7 minutes.
Arrange the dumplings in soup plates or bowls
Reheat the broth and divide it among the plates
Top each dumpling with trout roe.