For the steaks: Preheat the oven to 350 degrees Fahrenheit/150 degrees Celsius fan.

In a large ovenproof saucepan, for which you have a lid, combine the mushrooms, garlic, onion, chile flakes, red chile, cumin seeds, coriander seeds, tomato paste, olive oil, and salt and stir to mix. Arrange the mushrooms so they are domed-side up, then top with a piece of parchment paper, pushing it down to cover all the ingredients. Cover with the lid, then transfer to the oven for one hour. Turn the mushrooms over, replacing the paper and lid, and return to the oven for 20 minutes more, or until the mushrooms are very tender but not falling apart. Use a pair of tongs to transfer the mushrooms to a chopping board, then cut them in half and set aside.

Reserving the oil, use a spoon to transfer the onion, garlic, and chile (discarding the stem; don’t worry if you scoop up some of the spices and oil) into the bowl of a small food processor and blitz until smooth. Return the blitzed onion mixture to the saucepan, along with the mushroom halves, and place on medium-high heat. Cook for about five minutes, for all the flavors to come together.

For the mash: While the mushrooms are cooking, put the beans into a food processor along with the lemon juice, olive oil, water, and salt. Blitz until completely smooth. Transfer to a medium saucepan and cook on medium-high heat for about three minutes, stirring, until warmed through.

Divide the mash among four plates. Top with four mushroom halves per plate and spoon in a generous amount of the reserved oil and its accompanying aromatics (you won’t need all of it, though, as noted above). Serve at once.