Place the chickpeas, red onion, crushed garlic, parsley, coriander, cumin, pink salt, and flour in your food processor. Pulse the ingredients until they start to combine. Slowly add the olive oil as you pulse the mixture to help it combine. Make sure to stop every now and again to scrape down the sides of the food presser (this mixture sometimes sticks together too well!)
Put some oil on your hands and form the falafel mixture into 3-inch by roughly 1/2 inch (8 cm by 2 cm) patties.
In a large skillet or pan, heat oil over medium-high heat and fry the patties. Let them fry for about 5 minutes on one side. Once you start to see the patties browning on the sides, turn them over and fry for another 5 minutes. If you like your patties to be crisp, fry them for a few minutes more. Remove from pan and let the extra oil drain on some paper towels.
Assembling the burger:
Cut your buns in half and toast in the oven until lightly golden.
Spread your preferred condiments over the lower bun and add some fresh coriander. Add your patty, guacamole, relish and sliced tomato in no particular order, top it off with a lightly toasted bun and enjoy!