Start by softly cleaning the mushrooms under running water using a soft brush. Keep aside and allow to dry for 1 hour.
Place in a small bowl the oil along with the lemon, garlic, oregano, sea slat and whisk well to emulsify.
Turn the oven on at max temperature, grill on and rack set at the second highest position.
Take an oven proof dish and toss in the mushrooms. Brush all-over them the sauce and place in the oven cooking for 10-12’ flipping halfway through.
Remove from the oven and cut in chunks those mushrooms that are quite big. Season with the coarse salt and the pepper, drizzle some more oil and/or lemon and serve.