1. Heat up the BBQ or a frying pan on a medium high heat. Place the chicken thighs on a plate, season and drizzle with oil. Cook 4-5 minutes each side, or until the chicken is completely cooked through. Just before the chicken is cooked, place the bacon on the BBQ and cook until crispy.
2. In a bowl, mash the avocado with a fork. Mix the aioli, feta and mustard. Stir well and season if desired, then set aside.
3. Build the burgers. Split the buns in half. Spread the avocado mixture generously on the bottom half. Top with some red onion, salad leaves, a chicken thigh, two bacon rashers and some more avocado mixture.
4. Finish with the top half of the burger bun. Insert a cocktail stick to put together if liked. Serve with fresh lemon wedges.