Mist a frying pan with cooking spray and put over a medium heat. Add the spring onions and garlic, and cook for 2-3 minutes. Stir in the smoked paprika and cumin, and cook for 1 minute, then transfer to a mixing bowl.
Add the mince, mustard and beans to the bowl. Season to taste and combine. Shape into 4 patties, then chill in the fridge for 30 minutes.
Put a griddle or frying pan over a medium-high heat, brush the patties with the oil and fry for 3-4 minutes each side. Reduce the heat to low and cook for a further 5 minutes on each side.
Meanwhile, make the coleslaw. Put the cabbage, carrot and peppers in a serving bowl. In a separate bowl, whisk together the yogurt, vinegar and chives. Season to taste, then toss the dressing with the vegetables.
Top each bun base with tomatoes, gherkins and lettuce, then the burgers, coleslaw and bun top. Serve any extra coleslaw on the side.