Mark Moriarty's slow-cooked mushroom and halloumi burgers. Photograph: Harry Weir Sat Jun 27 2026 - 04:46Makes: 4Course: DinnerCooking Time: 5 minsPrep Time: 1 hr 30 minsIngredientsFor the mushroom butter:50g dried cepes80g softened butter1tsp onion powder1tsp garlic powderPinch of salt1tbs finely diced tarragon6 large portobello mushrooms 80g thick Greek yoghurtJuice and zest of half a limeSea salt and black pepper1tbs vegetable oil1x 250g block halloumi4 x brioche bunsHandful rocket leaves1tsp extra virgin olive oilStart by making your mushroom butter. Preheat the oven to 150 degrees.Add the dried cepes to a tray, place in the oven and cook for 15 minutes. Remove and place the cepes in a blender along with the onion powder and garlic powder.Blend to a fine powder and add to a mixing bowl with the soft butter and mix with a wooden spoon until combined evenly. Season with salt and stir through the tarragon, then set aside.Keep the oven at 150 degrees. Remove the stem from the portobello mushrooms, then peel them and discard the skin. Place the mushrooms on a large sheet of tinfoil. Spoon on and spread the mushroom butter on each mushroom, then wrap the mushrooms in the tinfoil to cover. Place on a tray and into the oven to cook for 90 minutes at 150 degrees.While the mushrooms are cooking, make the lime yoghurt. Place the yoghurt in a small bowl and season with lime juice and zest, salt and black pepper. Stir to evenly mix, then set aside. When the mushrooms come out of the oven, keep them wrapped in the tin foil to retain their heat, then place a nonstick pan on a medium heat and add the vegetable oil. Slice the halloumi about one centimetre thick and place in the pan. Cook for two to three minutes on a medium heat until golden brown on the base, then turn them and cook for two to three minutes on the other side until golden brown, then remove from the heat.To assemble, toast the brioche buns and spread some of the lime yoghurt on the base bun followed by the portobello mushrooms. Add some halloumi slices, then lightly dress the rocket in some olive oil and add on top of the halloumi. Mark MoriartyMark Moriarty is an award winning chef, TV host, author and Irish Times columnist.