For the beef patties
Mix all of the ingredients together, divide into palm-sized balls, flatten gently and then place on a plate in the fridge to firm up for about 30 minutes if you have the time.
Make the avocado topping by roughly mashing the avocado with a fork and adding the remaining ingredients. For the rostis:
Heat a frying pan over medium heat, add 1 Tbsp olive oil and soften the onions for 5 minutes. Remove and set aside.
Meanwhile, mix together the courgette ingredients, then leave to drain over a sieve for a few minutes, and gently squeeze out any excess juice.
Roll the mixture into palm-sized balls and then flatten gently until they are at least the same size as the beef patties, if not slightly wider in diameter.
Fry in 1-2 Tbsp olive oil for 2-3 minutes on each side or until golden and cooked through. They are careful as they have no flour to bind them together, so take care when frying and turning.
Drain on kitchen paper and then assemble the burgers and eat immediately.
Just sit the patty on a rosti and dollop the avocado on top and enjoy. Recipe reprinted with permission of SarahGraham. To see more recipes, click here.