Start by making the sauce. Place the sticky chilli sauce ingredients into your smallest saucepan and bring to the boil. Stir, and cook for a further 1-3 minutes until the sauce has reduced down to a runny syrup and then turn off the heat (it will thicker further as it cools).
Heat 1 tbsp of the oil in a frying pan (skillet) and fry the mushrooms with ⅛ tsp of salt and ⅛ tsp pepper until browned, then remove from the pan.
Add the remaining 1 tbsp of oil to the pan and heat.
Place the semolina in a shallow bowl and stir in the remaining ⅛ tsp of salt and ⅛ tsp pepper.
Crack the egg into a small shallow bowl and whisk lightly with a fork.
Dip the halloumi slices into the egg, then coat in the semolina.
Place the coated halloumi into the pan and fry on a medium-high heat for 2-3 minutes on each side – until golden brown.
Place bottoms of the two toasted brioche rolls on two plates and top with the lettuce and mushroom slices.
Once the halloumi is cooked, place it on top of the mushrooms. Top with slices of red onion and then drizzle over a little of the sauce. Place the top of the buns on the burgers and serve with any leftover sauce.
Can I make it ahead?You can make the sauce ahead of time, but it will thicken the more it cools, so you may need to reheat lightly before serving. Make the sauce, then cool, transfer to a container, cover and refrigerate until it's time to reheat. This recipe only makes a small amount of sauce so if you're making it ahead, it might be worth making double, as it's quite hard to transfer and reheat such small quantities.I don't recommend making the burger ahead of time. Fried halloumi tastes best when freshly fried.Ingredient Swaps
Swap the sliced red onion for thinly sliced strips of spring onion (scallions)
Swap the mushrooms for lightly fried sliced peppers
If you don't want the sticky sauce to be spicy, swap the sriracha for tomato ketchup