Add all of the ingredients into a medium sized mixing bowl. Whisk to combine. Use tongs to take the chicken out of the marinade and allow excess to drip off before placing into the bowl with the coating. Flip it around ensuring you coat the chicken well in the crumb mixture. Then place on top of a cooling rack with a baking tray underneath.
Fill your large pot with an inch of vegetable oil to 175°C / 350°F. To test the oil temperature, add some crumbs in the oil and if it bubbles then it’s ready. Place two pieces of chicken in at a time and cook until golden brown. It will take about 3-5 minutes on each side. If the chicken browns too quickly, you need to turn your temperature down. Place back on the cooling rack and allow to sit for 3-4 minutes. The internal temperature of the chicken should be 75°C / 165°F.
To assemble the chicken burgers, lightly butter both sides of the brioche buns with butter. Place on a very hot fry pan and toast until golden brown. Alternatively, you can grill them using the grill setting on your oven.
Add some mayo on one side, bqq sauce on the other and then add the lettuce, tomato slices, pickles and onion on the bottom half of the bun, followed by the chicken. Serve immediately!