Heat a drizzle of olive oil in a large frying pan over medium heat. Add the sliced onions, maple syrup and a pinch of salt. Cook for 25 minutes, stirring regularly, until the onions are deeply golden and soft. Add small splashes of water if the pan becomes dry. Set aside.
In a small bowl, combine the Greek yoghurt, ketchup, mustard, garlic powder, coconut sugar and diced pickles. Mix well and set aside.
Divide the mince into 8 equal balls. Place one ball onto each tortilla and press firmly with your hands to spread the meat in a thin layer right to the edges of the tortilla. Sprinkle generously with the BBQ seasoning.
Heat a large frying pan or griddle over medium-high heat. Place the tacos meat-side down and cook for 2–3 minutes, pressing lightly so the meat browns and crisps.
Flip the tacos so the tortilla side is down. Place a slice of cheese on the meat, cover the pan and cook for 1-2 minutes, until the cheese melts and the tortilla is lightly toasted. Repeat with remaining tacos.
Top each taco with shredded lettuce, caramelised onions, burger sauce and a sprinkle of fresh parsley. Serve immediately.
