Heat a non-stick frying pan over a medium to high heat. Add half the oil with the butter and sauté the spring onions, courgettes and carrots for 5 minutes until softened and just starting to catch a bit of colour.
Stir the Quorn mince into the pan and sauté for another 1-2 minutes until lightly browned. Leave to cool.
Place the cooled vegetable and Quorn mixture into a bowl with the breadcrumbs, curry paste, peanut butter, egg and parsley. Season with a pinch of salt and plenty of pepper and mix well to combine.
Using slightly wetted hands, shape the mixture into four x 10cm patties. Cover and chill for at least 30 minutes (or up to 24 hours) to allow the mixture to firm up.
When ready to cook, brush the chilled burgers with the rest of the oil. Wipe out the frying pan and place over a medium heat. Add the burgers and cook for 5-6 minutes on each side until heated through and lightly golden.
Toast the buns, cut side down on a hot griddle pan for a couple minutes. Arrange the avocado slices on the bottom halves and put the burgers on top. Add a small mound of the red cabbage and the burger tops to serve.