I toyed with calling this dish ‘mushrooms in anchovy sauce’ or ‘anchovies in mushroom sauce’ but neither quite fitted nor did it justice. It needs a base of butter-soft blandness to temper its wildness of flavour, so serve it atop a pile of creamy mash or plain pasta, and enjoy. The bolder the mushrooms the better the finished product, so choose from farmhouse, baby portobello, shiitake, wild, ceps or a mixture of whatever you can find. Plain white standard mushrooms also work, if you can’t find a bolder variety, but the more exotic ones are worth seeking out.
First peel your onion and finely slice it. (I use a mandolin to make short work of this, and a pair of ski goggles to protect my eyes, because sometimes chopping onions can be overwhelmingly off-putting. Of course, you can also use bags of frozen sliced onions, and I do that too, but for the sake of writing a recipe book and Seeming Proper, I’m pretending here that we start with a whole onion.)
Toss your onion into a wide, shallow nonstick pan. Open the tin or jar of anchovies carefully and pour their oil into the pan over the onions, then set the anchovies to one side for a moment. Set the pan over medium heat and gently cook the onions for 7–8 minutes, stirring intermittently to disturb them so they cook evenly and do not stick or burn.
Meanwhile, slice your mushrooms to around 3mm thick. Add these to the pan and stir in. Tip in your anchovies and break them up roughly with the side of your wooden spoon, and stir through along with the herbs. Add the butter or oil and cook for a further 10 minutes, turning the heat down to low when the mushrooms start to soften.
Finish with the vinegar, and stir through. Season to taste with black pepper – it will be plenty salty enough with the residual anchovy – and serve over your carb of choice.
This is one of those dishes that is even better the next day, so if you have any left, allow it to cool then chill in the fridge, then warm back through thoroughly to serve. It doesn’t freeze particularly well as it isn’t very saucy, but it will keep for 48 hours in the fridge. Any longer and the mushrooms start to turn a little sluggish, which isn’t pleasant.
© Jack Monroe, 2020