Pour the oil into a heavy-bottomed pan or flameproof casserole that comes with a lid, and put it on a low to medium heat. Add the parsley, lemon zest and chili flakes and grate in (or mince and add) the garlic, and let them sizzle fragrantly, but briefly as you don’t want them to burn or, really, do anything other than infuse the oil with their scent.
Turn up the heat, add the mushrooms, sprinkle with the salt, and give a gentle stir to try to mix the flavored oil, then clamp on the lid. Turn the heat down to low and leave everything to simmer for 10mins. Although the mushrooms look dangerously dry as you put the lid on, when you remove the lid after 10mins, you will see that they have given off quite a bit of liquid.
Now add the juice of the lemon, give everything a vigorous stir, then put the lid back on for another 10mins, simmering until the mushrooms are tender. It’s wise to have a look once or twice during that time – just lift the lid and give a bit of a stir.
Scatter a little more parsley over the mushrooms, and serve.