• Rinse the quinoa well and cook according to the package instructions. Once cooked, divide the quinoa in to 3 half cups.
• Preheat the oven to 180 degrees C (356 degrees F) and cut the cauliflower in to florets before placing them in a roasting tray. Drizzle with the olive oil and season well with sea salt. Roast in the oven for 15-20 minutes and remove to cool. 
• When cooled, chop half the cauliflower in to small chunks (set them aside) and place the other half in a food processor with a half-cup of the cooked quinoa, the full cup of chickpeas and the coriander. 
• Add the aquafaba, a spoon at a time, and pulse the processor until the chickpeas are smooth and holding the mixture together. 
• Transfer the mixture to a large bowl and add the remaining cauliflower (that's the chopped cauliflower from earlier), another half-cup of quinoa, the cheese, sea salt and breadcrumbs and stir together. Using your clean hands, test that the mixture comes together in to a patty. Add more breadcrumbs if necessary. 
• Line a tray with grease proof paper and add the last half-cup of cooked quinoa to a plate.
• Form the burger mixture in to small palm sized patties and gently press them in to the quinoa (you can press the quinoa in to the patties if that's easier) before laying the burgers on the lined tray. When all burgers are ready, place the tray in the fridge for 30-minutes.

To Prepare the Toppings

• To dress the lettuce leaves place them in a bowl with the lemon zest, a pinch of sea salt, and a wee splash of olive oil.
• For the sriracha mayonnaise, combine the vegan mayonnaise and sriracha sauce (add more or less to taste) in a small bowl. Cut the burger buns in half and lightly brush the cut side with oil for toasting. 

To Finish the Burger

• Heat a large skillet over medium heat and add a tablespoon of sunflower oil. Take the burgers from the fridge and add them in batches of three or four to the hot pan. Cook for three minutes or until a crisp seal forms on the bottom of the burger. Turn the heat down slightly and cook for another minute. Gently flip the burger and cook the other side for another three minutes. Repeat with the remaining patties. 
• While the burgers are cooking, heat another pan on low to medium heat and gently toast the burger burger bun, cut side down. Remove from the heat and add a good dollop of sriracha mayonnaise to the bun base and top with a burger patty. Top the burger with lettuce and avocado (if adding) and top with the bun lid. Repeat with the other burgers and serve.