Mushroom faux-gras

If you’ve hung out in our house at any point this Autumn, chances are you’ve eaten this luscious mushroom faux-gras. It starts off as a dark pâté, with mushroom, but also browned leeks and shallots for some heft, and a hint of smoked paprika for heat. It’s then set with agar-agar to form a thick creamy, yet crumbly, jelly, perfect for slicing and spreading on truffled baguettes, crispbreads (or Ryvita thins in a pinch) or just on hot buttered toast for the after-party. It’s also a great vegetarian substitute for foie gras, which, while delicious, is rather hard to digest ethically.

Mushroom faux-gras with towers of truffled baguette
Mushroom faux-gras with towers of truffled baguette

This recipe was originally inspired by an episode of America’s Test Kitchen Radio where they interviewed Amanda Cohen from NYC’s Dirt Candy. I’m not a vegetarian, but I love the idea of featuring vegetables for their strengths, rather than using them only as sides, or to make poor-man’s versions of meat dishes [and yes, I advertised this as a vegetarian version of foie gras, but that was just to get your attention! Try it, and you’ll love it, I promise you!]

The Dirt Candy portobello mousse, as they call it, is legendary, and a full recipe for the dish with all the trimmings, is here. I made a bunch of tweaks, mostly to make it a standalone dish. If you’re not making a balsamic reduction, and grilling mushrooms etc, it’s worth giving the faux-gras itself a bit more depth.

It would be a bit pointless to advertise this as a vegetarian dish, and then use gelatine. If you’re fine with using gelatine, which is more easily available, go ahead. However, the setting properties of agar-agar are slightly different, and it gives the final jelly a more crumbly texture – making it look more like foie gras. I imagine a jelly set with gelatine will spread quite differently on toast, so it might be worth it to just cut the amount of cream slightly and serve this as a thick pâté to be scooped up instead.  You’ll have all of the flavour, but less of the pizzazz!

An aside on the chemistry of agar agar

Agar-agar, or china grass as it’s often called in India, is extracted from seaweed and sold as flakes. A detailed explanation of the chemistry behind it is here, but basically, here are the 3 main things you need to know to work with agar-agar:

  1. It needs to be dispersed fully and then heated in order to become activated
  2. It sets at around 35-40°C
  3. Once it’s set, it remains set until it reaches 80-90°C

For the science geeks out there, this means that agar-agar has a certain hysterisis, or temperature interval between the melting temperature and the gelling temperature. So once it gels, you can take it out, and warm it and it will remain a gel. How cool is that!

In practice, this means we will need to disperse the agar-agar well, by whisking it in a liquid, and then boiling the mixture so that it gets activated. We then cool it to form the jelly, and voila, we can serve this at room temperature or warmer, and it will remain a jelly!

Mushroom faux-gras

4 large portobello mushrooms
1 leek
2 shallots
1 cup double cream
12 tbsp butter
2 tbsp truffle oil
1 tsp paprika
1 tsp ground black pepper
1 level tsp agar-agar
A loaf pan, lined with parchment paper
A mixie or standing mixer that purées food very finely
Prep time: 15 min; Cook time: 20-30 min; Chill overnight before serving. Adapted from Dirt Candy NYC’s Portobello Mousse recipe

I don’t bother with peeling portobellos, especially when they’re going to be blitzed later anyway. Roughly chop 3.5 portobello mushrooms, the leeks, and 1 of the shallots, and set aside.

Roughly chop 3.5 portobello mushrooms, the leeks, and 1 of the shallots, and set aside.

In a pan, warm 2 tbsp of butter, and once hot, add the chopped leeks and shallots and set on a medium heat. Once the leeks have sweated and the shallots have gone golden brown (about 5-8 mins), add in the chopped mushrooms and let them cook for another 3-5 mins.

Add the remaining 10tbsp of butter to this mixture and let it melt in the heat. Also add the spices and truffle oil, and adjust to taste. You can add in a pinch of salt of you’d like at this point.

Transfer this mixture to the mixie and let it cool completely. (Be patient here, the last thing you want to do is grind a hot mixture, which usually causes the lid to fly off, sending the mixture all over your freshly-cleaned kitchen.)

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Meanwhile, dice the remaining 0.5 portobello mushroom and finely dice the other shallot. Separately roast these in a hot pan until they’re nicely browned. Set aside.

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Line your loaf pan with parchment, and sprinkle the browned shallots and portobello on the bottom. Once inverted, this will form the top of your faux-gras. Do not use foil, since agar-agar apparently refuses to set when it comes in contact with foil! (I can’t remember where I read this, and google failed to turn up a convincing reason, but there you go.)

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The mushroom-leek-shallot mixture should have cooled now. Add the cream to it, and the agar-agar, and blitz until completely puréed. Add this back to the pan, and heat until it starts boiling.

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If you’d like to test whether your mixture will set, take a small amount (1/2 tsp) of the mixture and place it in a bowl filled with ice-cold water. In a minute or so the mixture should solidify, giving you an indication of what the end result will look like!

Now pour the mixture into the loaf pan, and smooth the top (which will become the base of your jelly). Let it cool before popping it into the fridge to chill overnight.

Pull out, invert, enjoy. You can serve this with store-bought crispbreads, or toast. I also served these on one occasion with thin slices of baguette which had been drizzled with olive oil + truffle oil, and toasted in the oven at 200°C for about 8-10 mins.

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