Easy bean burgers with potato wedges

Name: Easy bean burgers with potato wedges
Ingredients: 800g/1lb 12oz large potatoes, each cut into 8 wedges; 2 tbsp vegetable oil, plus 2 tsp; ½ tsp paprika (optional); 150ml/¼ pint soured cream or crème fraîche; 1 spring onion, trimmed and finely sliced (optional); ¼ iceberg lettuce, trimmed and shredded; 4 seeded burger buns, split; salt and ground black pepper; 400g tin red kidney beans, drained; 2 spring onions, trimmed and finely sliced; 1 tsp ground cumin; ½ small lemon, finely grated zest only; 20g/¾oz plain flour; ¼ tsp fine salt