Drain and rinse the blackbeans, then put them in a bowl and mash them a little with a fork so that some of them break up and others remain whole.
Add the chopped herbs, grated Parmesan, mustard, lemon juice, eggs and seasoning and mix well together.
Add the dried breadcrumbs and mix in, then leave for at least 5 minutes before forming into 4 burger shapes.They are now ready to cook. Or, you can get them to this stage in advance and keep in the fridge (up to 24 hours). They also freeze well. Defrost before cooking.
To cook, preheat the oven to 190 degrees C. Heat the olive oil in a large oven-proof frying pan over a medium heat. When hot, put the burgers in the pan and cook for about 2-3 minutes on each side, until browned.
Transfer the pan to the oven and bake for about 10 minutes, until cooked through (they should be quite firm to touch).
Optional - add a finely chopped chilli to the mixture.
If you don't have an oven-proof frying pan, simply transfer the burgers to a baking tray when they are ready for the oven.
*e.g. Paxo (blue pot), Panko (Japanese breadcrumbs) or homemade. For homemade, blitz leftover bread in a food processor and keep the crumbs in the freezer - for this recipe you can use them frozen. Or toast the blitzed breadcrumbs on a baking sheet in a 180 C oven for about 10-15 minutes. When crispy and golden, leave to cool on the tray before storing in a jar or other airtight container.
** e.g. coriander / parsley / dill / thyme /basil.