1/ Wash and finely slice the leek. Crush the fennel seeds. Drain the beans and then use a stick blender or potato masher to crush them. Don’t blend them until they’re completely smooth you want to still have a few bigger bits of beans in there. Remove the sausage meat from the sausages by using a sharp knife to score the skin and peel it off.
2/ Heat the oil in a pan and then add the leeks. Cook for a good 10-15 mins until they have softened and are starting to brown round the edges. Put to one side to cool.
3/ Once the leeks have cooled put all the ingredients into a bowl and mix really well, it’s easiest to use your hand. Divide the mixture into 6 equal parts and, one at a time roll each part to make a sphere and then flatten it between your palms. Lay the burgers on a tray lined with baking paper and place them in the fridge for at least half an hr. (You can also freeze them at this stage).
4/ Cook them under hot a grill or on a BBQ for 8 – 10 mins each side until they’re cooked through or in an airfryer at 200℃ for 16 mins.