“A satisfying supper that’s a brilliant way to use leftover vegetables and ham. It’s a pretty loose recipe – you want the burgers to hold together, so you need enough vegetables to bind the ham, but you don’t want too much veg, or the texture will be overly mushy. ”
Peel and slice the onion, then place in a small bowl. Cover with the vinegar and set aside.
Mash all the veg well with a potato masher, then shred add the ham and season generously. Mix together well, then shape into 4 burgers and chill in the fridge to firm up, until ready to use.
Heat the butter and oil in a large frying pan over a medium heat and cook the burgers, in batches if needed, for 3 to 5 minutes each side or until crisping up and turning golden brown.
To serve, slice the muffins or burger rolls in half and fill with the bubble and squeak hamburgers, pickled red onion, lettuce and ketchup, if desired.