Step 1

Cut the stem of the mushroom and brush any excess soil with a damp cloth.

Step 2

Into a small bowl, add olive oil, parsley, chilli flakes and a small pinch of salt and pepper. Mix thoroughly. Using a basting brush, brush olive oil mixture all over the mushroom, making sure it’s all covered.

Step 3

On a small nonstick pan, heat over a medium heat. Cook mushroom for 4-6 minutes on each side, covering it with a lid to steam. Whilst this is cooking, on another small nonstick pan, splash a small amount of olive oil and heat on high. Add onions into the pan with a pinch of salt and cook for 5 minutes.

Step 4

Take onion out of the pan and add haloumi. Cook until lightly golden brown on each side.

Step 5

Toast the bread under the grill for 2-3 minutes until lightly toasted.

Step 6

In a small bowl, add pesto and mayonnaise into a bowl and mix.

Step 7

It’s time to STACK! On the bottom of the burger bun, smear mayonnaise mixture edge to edge. Add mushroom, onions, haloumi, tomato and lettuce leaves and serve.