Mushroom, quinoa & bean burgers with slaw & miso mayo

Ingredients

• 75g/ a third of a cup quinoa, rinsed
• 400g can butter beans, drained
• 3 tablespoons olive oil
• 1 onion, chopped
• 2 cloves garlic, crushed
• 1 egg, beaten
• quarter of a cup finely chopped flat leaf parsley
• 6- 8 large Portobello mushrooms
• quarter of a cup mayonnaise
• 1 tablespoon white miso paste
• 1 tablespoon lemon juice
• to serve: 6-8 warm burger buns and finely sliced cabbage, carrot, red onion