Heat the oil in a griddle or frying pan and lightly fry the onions for a few minutes. Then add in the mushrooms and cook until tender and brown.
Add the onions and mushrooms to the mince, breadcrumbs and herbs and mix together in a food processor. If you don’t have a food processor make sure the ingredients are all finely chopped and mix well with your hands to bind it all together.
Shape handfuls of the mince into burgers using lightly floured hands.
Cook the burgers for 12-15 minutes in the frying pan or griddle. Turn once, until evenly cooked throughout.