Mix the beef with salt and pepper and the chilli flakes and form into patties that are just larger than the width of the avocado. Aim to make them 2 centimeters thick, so they still stay medium when cooked.
Mix the Sriracha with the mayo and set aside.
Take the avocado and instead of cutting in half lengthways, lay the avocado on your board and chop across horizontally. Using the back of a teaspoon, gently prise the skin off.
Carefully remove the stone from one of the halves. The pointy top end of the avocado will form the base 'bun'
And make a slice towards the bottom to give it a flat bottom so it will sit upright. The rounded bottom of the avocado will form the top part of the 'bun', and lightly drizzle these in the sesame seeds. Set aside.
Place the burger in a hot pan and caramelised on one side for 1 minute, before flipping over, adding cheese and placing under a hot grill until just melted.
Meanwhile, fry the bacon and set aside.
To assemble, sit the bottom bun facing up (the stone hole will face up) and place some mayo on top, followed by leaves of spinach on top. Add the cheese burger to this followed by the bacon and top with the top 'bun' of avocado, with the seeds facing upwards.